swf strange behaviour

I’m having som weird issues with swf exported from Animate. What happens is this: all my animation is drawn and colored in Animate. I export some seconds of a walk cycle as swf. I import the file into after effects, playback looks fine. Then after a while (hours/days) the swf wont play as it should in After Effects. Suddenly one or more frames of the walk cycle is duplicated, and the walkcycle stops and jerks. I open the swf in flash player and the error shows up there too. Import the swf into Flash, same thing happens. Any idea what this could be? Seems like the problem origins from Animate since the original swf from Animate is damaged. After Effects merely plays back the file.