Layers disappearing on test movie/exporting

Hello. Encoding the movie seems to be making random layers disappear entirely. This was an issue in testing the movie too, but I didn't think it'd carry over into exporting the movie. I was willing to deal with it because at least layers/frames displayed correctly on the stage itself. But if it's going to export the problem I have to know how to fix it. Please help :c None of the layers are set to guide, and the scene has 1323 frames so far with many, many layers (just in case this is relevant)