Hi, I have found other older threads about this problem but write one myself since the solutions/workarounds mentioned in the other threads don’t work for me.
So, the problem is that blender sometimes lag 1 frame when updating the armatures animation. To be more specific I have a pretty complex human’ish armature (based on the one from Rigify) and there are some bones driven by a chain of constraints that lag. I don’t know why the rest of the armature isn’t affected though.
Here is my .blend and a pic of which bones that lag:
There’s no animation in the file you posted, but these lags are usually the result of a dependency cycle. Bone A depends on bone B, which depends on bone C, which depends on bone A… that sort of thing.
Unfortunately I couldn’t locate it, but try running blender from a console, any circular dependencies should show.