I wouldn't say these movies were necessarily "panned", but I think the closest movies I can think of would be Operation Avalanche and Under the Silver Lake.
Both of them wound up being tremendously interesting movies, which didn't execute their premise flawlessly, but executed it well enough for the movies to really work for me. I love both of these movies despite their flaws and while I can certainly imagine some people not being able to get past those issues, I'd still strongly recommend them if you are into cinema.
To briefly sell them, Operation Avalanche is a political thriller type movie from the makers of The Dirties (another fantastic film) which portrays in a mock-documentary period piece, how the CIA faked the moon landing. While the character writing doesn't always feel appropriate for the period, I found the story itself extremely engaging and it all uses it's low budget to amazing effect to really sell the mock-documentary aspects. They actually managed to film a lot of the story on location in NASA with interviews from a lot of NASA employees by pretending that they were making a PBS style documentary. The entire making of this film is fascinating and it resulted in a project which is nothing like anything else I've ever seen and I love it for that.
Under the Silver Lake is a bizarre and extremely ambitious project from the director of It Follows, which explores Hollywood and pop culture conspiracy (turn out conspiracy movies can be real interesting), but while Operation Avalanche tells a pretty clean and concise story, Under the Silver Lake just goes all over the place. It is an absolute journey of a film and while not all of the plot threads feel like they are tied up, it kind of makes it have the feeling of something like the old X-Men movies where these ideas are cameos hinting at a world beyond the film.
Both of these films have an energy to them which make it feel like the creators were really having fun experimenting and trying things out. While they don't always nail the polish, they do manage to be unique and memorable and I hope enough people watch them that the creators can keep experimenting with future projects.