Glad you solved it Ingmar.
It’s sounds like you had a very frustrating time while I was asleep.
There’s 2 things you need to be aware of those.
You are right, sometimes it doesn’t playback 100% in sync. Maybe you had Chrome open it was taking up all your RAM for a millisecond, or your email was trying to sync or whatever.
So yeah, you need to watch it over and over, and make sure you check the actual video output.
The other thing is that often want the shapes to be ahead of the sound by about 1-2 frames. So when you are animating by scrubbing they will generally be smack bang on the sound, so you need to shift some of them. (some animator’s do it all smack bang on and then shift the entire thing 2 frames ahead, but I think each shape/sound needs to be shifted the required amount – it’s different in each circumstance)
Hope some of that makes sense.