That’s certainly very odd. The only thing coming to my mind is that somehow, some repeat barlines have Suppress Playback activated but that’s not something that can really happen by accident. As so often, if you post the project file this will be much easier to investigate.
Edit: I saw that you had uploaded this project in another thread. Perhaps disappointingly, when I play back the version of the file from your post earlier today all the repeats and endings just work as they’re written. As a very basic test, if you save the file, quit Dorico and then reopen it, does the oddness persist for you?