Hey, got a trouble with cache, here is the deal :
Animation data modifier don’t tag raw data as Modified and i can call mark it manually from my anim modifier
thus the cacheKey isn’t updated and thus animation isn’t re compressed
the only way is to manually edit a value ( on a curve ) so the editor set it modified for you or clear the derived data cache ( as it will for recompresse ), but non of those are really a practical solution .
As i add a curve to animation sequence, if i try to package i have some
Ensure condition failed: !bUseRawDataOnly
Anim Compression failed for Sequence xxx
so is there a way to manually tag that data as modified ( call “UAnimSequenceBase::MarkRawDataAsModified” ? )
i will make a c++ helper for my case, but it’s just to save someone else time if you are in the same situation 
and know if i should report to epic or not