Zoe Elton, director of programming for the Mill Valley Film Festival, was calling from the Telluride Film Festival, just minutes before leaving to catch a screening. Normally, the event in Colorado, one of the most prestigious on the film festival circuit, would be hosting some of the most recognizable faces in Hollywood for star-studdeed talkbacks following movie premieres. This year, though, Q&As and panels featured more of the folks behind the cameras, virtually devoid of movie stars who are on strike.

Still, Elton noted, the vibe was “very celebratory.”

“It’s kind of like we’re in a cinema summer camp,” she said.

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少数明星出现在劳动节我们ekend event included Ethan Hawke — wearing a “Strike” T-shirt — in support of “Wildcat,” which he directed and which stars his daughter, Maya Hawke, as novelist Flannery O’Connor.Emma Stone“可怜的家伙”,他的电影etting raves, didn’t promote the film — director Yorgos Lanthimos did a Q&A — but was at Telluride, apparently having bought a festival pass.

Then there was Julia Louis-Dreyfus, who was attending her first Telluride and, though otherwise on strike, promoting her film “Tuesday.” The actors’ union,SAG-AFTRA, reached an interim agreement with A24, which produced the film and agreed to the union’s financial terms. So far, major studios, under the umbrella of the Alliance of Motion Picture Television Producers, are refusing to meet SAG-AFTRA’s demands.

“As a proud member of the Screen Actors Guild for the last 41 years, I stand here in solidarity with my union and the WGA,” Louis-Dreyfus, who has spent time on the picket lines and was also seen at the festival wearing a strike shirt,told the media. “If smaller studios like A24 can agree to what my fellow brothers and sisters deserve, why can’t the AMPTP?”

Good question.

Just when it appeared that the“Barbenheimer”effect would save a theatrical movie market that has still not recovered to pre-pandemic levels, along came Hollywood’s work stoppage. The effects of the strikes by the Writers Guild of America, which walked out on May 2, and SAG-AFTRA, which joined writers on the picket lines in July, are now clearly being felt.

Not only are actors not working, they’re not promoting. That has already affected the late summer box office, shifted the fall schedule and is upending major film festivals — including October’s Mill Valley event — that are considered key opportunities to launch Oscar campaigns.

“The strikes really put up front and center a lot of things in the business that have not changed, even as streaming in particular has been integrated into the way that we see stories,” Elton told the Chronicle. “Whether it has to do with actors not getting residuals in ways that they would have gotten in the golden days of television, or whether it has to do with the reality and the fear of AI, it’s like it’s all coming to a big head right now.

“I think this is the next phase of an identity crisis — sort of a reset in how we work as a business.”

Again, this is a big-studio problem. On the opening night at the Venice Film Festival on Aug. 30, actorAdam Driverwas one of the few stars to show up, promoting Michael Mann’s “Ferrari,” which stars Driver as the sports car maker Enzo Ferrari. Like Louis-Dreyfus, he was able to promote it because the movie is being released by an indie distributor, in this case Neon, which has agreed to terms with the striking unions.

“I’m proud to be here, to be a visual representation of a movie that’s not part of the AMPTP,” Driver said at his Venice news conference. “Why is it that a smaller distribution company like Neon and STX International can meet the dream demands of what SAG is asking for — the dream version of SAG’s wish list — but a big company like Netflix and Amazon can’t?”

Or, for that matter, big studios like Warner Bros., Disney and Sony, among others.

The summer’s two breakout hits —“Barbie”($1.38 billion globallythrough Monday, Sept. 4) and“Oppenheimer”($850 million) — both opened on July 21, and major actors from both films were able to promote them before the strike was called on July 14.

But in August, two of the films with the biggest expectations, the DC superhero flick“Blue Beetle”and the raunchy animal comedy“Strays”opened to tepid box office numbers, $25.4 million and $8.2 million, respectively.

“Strays” features the voices ofWill Ferrell,Jamie Foxx,Randall ParkandIsla Fisher— all on strike. And because “Blue Beetle” star Xolo Maridueña, who already had a fan base through his role on Netflix’s “Cobra Kai,” could not promote the film, Warner Bros. pulled it from late July’s Comic-Con in San Diego.

An outlier: The name “Denzel Washington” apparently was all the promotion needed for “The Equalizer 3,” which pulled in $42.3 million for the second-biggest Labor Day weekend opening, behind “Shang-Chi and the Legend of the Ten Rings” in 2021.

Nonetheless, box office analyst David A. Gross told the New York Times last month that the lack of celebrity promotion likely costs a film 10%-15% at the box office. Studios must agree with that assessment. Soon after August’s box-office numbers were posted, films began dropping off the fall release schedule.

Two movies with megastar and Oakland nativeZendaya, the tennis love triangle “Challengers” and the highly anticipated sci-fi epic “Dune: Part Two,” were pushed back to the spring of 2024. Sony moved its Marvel film “Kraven the Hunter” back almost a year, but it was too late to pull back Esquire’s September cover story on star Aaron Taylor-Johnson. Sony also moved its “Ghostbusters” sequel from December to March.

This all means ourChronicle fall movie previewlist should be taken with a hefty grain of salt. Much could change in the weeks ahead.

One thing that won’t change are the dates of the Mill Valley Film Festival, set for Oct. 5-15. It is the biggest star-driven festival in the Bay Area, and akey stop for films with Oscar aspirations. On the festival circuit, the Oscar campaign season begins with Venice and Telluride, moves to Toronto and then hits both coasts with the New York and Mill Valley festivals.

Last year, for example, Mill Valley paid tribute toBrendan Fraser, who eventually won the best actor Oscar for “The Whale,” and also hostedKate Hudson(“Glass Onion: A Knives Out Mystery”) andEddie Redmayne(“The Good Nurse”).

This year, it’s all about directors, includingSofia Coppola(“Priscilla”),Emerald Fennell(“Saltburn”) andTodd Haynes(“May December”).

“I think at its heart, Mill Valley has always really been about filmmakers and about creative storytelling,” Elton said. “While the big stars are a part of that, they’re not the only part of that. My hope this year is that people will gravitate towards the core sensibility of why we make films and why we tell stories. You know, it’s really about the human condition.”

That said, there are rumors that the strikes might end in early October. If that happens, Mill Valley Film Executive Director Mark Fishkin said he expects his team to hit the phones immediately as part of a “huge scramble to have them here.”

The “them” he is referring to, of course, are movie stars.

Reach G. Allen Johnson: ajohnson@sfchronicle.com