There probably IS a way to fix it, but I hope you're prepared to set aside a couple-three days to 1) diagnose the cause and 2) apply the fix.
There's no telling what the problem might be at the moment. But there are some pretty good diagnosticians on the forum.
I think Dave is correct, this might be an odd one to track down. That's clearly not supposed to do that!
What format/codec is the footage? Where is it stored?
Also, are you using CC 2015 or CC 2015.3 where it works correctly?
In fact, while we're at it, what's the exact version number of AE that works and the exact version number of the one that doesn't work?
Thanks for your answer, guys. I tried searching the forum, but I didn't really found something.
The videos are screenrecordings of an iPhone via Quicktime. So the are h.264 movs. They are stored on a network file server.
The AE file was created with 13.7.2. I installed 188.8.131.52 now and it works. In 184.108.40.206 the timing is off.
I just had a look at the frame rates of the videos. It seems the different AE version interpret them differently. One video is 60fps in 13.8. (right timing), but in 220.127.116.11 (wrong timing) it shows as 30,196fps. What really adds to the confusion is that quicktime says the video file has a frame rate of 39,14.
If it was just a problem with the video files and not AE, both versions would behave the same way though, right?
There are known bugs in some iPhone footage causing different apps to interpret the frame rate differently. You really need to pay attention to this when you import all footage from any source. Make sure that it is correct. Your iPhone footage should either be 29.97, 23.976 or if you insist on shooting at a high frame rate, 59.94 fps. The only way to know exactly what the true frame rate of your iPhone footage is would be to film a very accurate stopwatch for two or three minutes, import the footage, check the total number of frames and do the division. Unless something is really screwed up with the iPhone or you need time accuracy down to the hundredth of a second the standard frame rates will work perfectly with your footage and your product will be fully compatible with media players, tv sets and any other device you use to view your movie.
Your problem can be solved by selecting the footage in the Project Panel and choosing File>Interpret Footage>Main (Alt/Option + Ctrl/Cmnd + g) and fixing the frame rate of the footage so it matches the original frame rate in your previous project.
Unless you have specific reasons to use and shoot 60fps you should be using 29.97 or 23.976 fps because that is the standard for NTSC countries. There are definite visual differences with different frame rates because of motion blur, shutter speed and the interaction of the frame rate and the speed of objects moving in the frame. 60fps footage looks less cinematic and if there is a lot of movement in the frame create an entirely different emotional response from the same shot, so if you want your video to look more like a movie you should produce the final product at 29.97 or 23.976 fps and set your iPhone to record at 30 or 24.
Hey Rick, that's very interesting. Thank you. Does this apply to screen recordings of iPhones as well though? Because my footage is not a video recorded with an iPhone, but a screen capture done with Quicktime.
Yes. The metadata is not consistently recorded correctly. I always check the interpreted frame rate of my footage and make sure that it is correct. You would be surprised at how many time I have seen 30.136 fps or something like that from screen recordings and consumer cameras. Changing the frame rate from 30.16 or anything close to 30 to the standard frame rate of 29.97 is not going to make any significant change in the audio and unless you are timing the action with a stopwatch you won't notice a difference in playback speed either. It's always best to stick with the standards.