Hey @NanL, this is actually a pretty common off-by-one quirk when you bring an Alembic cache into Unreal. Maya treats your frame range as inclusive so if you bake 1–40, you really get frame 40, whereas Unreal’s Geometry Cache importer treats the end frame as exclusive (so telling it to import 1–40 really gives you 1–39). FBX animations don’t hit this snag because Unreal maps their duration differently and always includes the last frame.
To work around it, you’ve got two easy options: either export one extra frame from Maya (so bake 1–41) and keep Unreal’s import at 1–40, or manually set the Unreal import range to 1–41 (so you grab everything up to but not including frame 41). Either way, your “frame 40” data lands where you expect it.
I know this reply is coming very late but hopefully someone else could make a use of it..