I have been kind of tearing my hair out trying to figure this out. I have a frame animation with 30 frames. I tried exporting it as a video set to 12fps. For some reason, what should be 2.5 seconds (30 frames at 12fps) is dropping down to 2 seconds on export. I thought it was some weird video codec glitch, but I discovered that the same thing happens when I export as an image sequence: Even though I have checked several times that "All Frames" was selected (other options are disabled anyway), I find only 24 pngs in my sequence where there should be 30.
Any help with this? It's a frame-by-frame rotoscoped animation so switching from frame animation to a timeline animation doesn't quite work. I know I can export frames manually by saving each frame one at a time, but it would be lovely to not have to do that (or to find a script that can do this for me to save time).
I'll gladly share screenshots later tonight when I'm at my animation computer again.