We ran into this problem recently and it might be the case that the Skeletal Mesh is prohibiting the animations, like ignoring it due to the skeletal adjustments properties. We adjusted the rig to have the fingers squeeze the handle of a weapon tighter in the Cinematic Trailer and no animations could be updated, changed, or added after the finger bone’s adjustment.
Our Solution: Delete the “Sequencer” adjustments and create a separate animation the does the finger adjustments or head movements and add them in Animation tracks.
Hope that helps at all.