Question reimport of rig/animation does not apply

This has been dogging me for over a year, and I see no way why it should be happening.

I make an adjustment to an animation in Blender, export.
I have a rig and SkinnedMeshRenderer (SMR) parented to an object in Unity, in the heirarchy, not a prefab.
The adjustment to the animation does not appear.

The only way I have found to make it appear, is to delete the rig, delete the SMR, drag the FBX into heirarchy, copy the rig and SMR from the FBX in heirarchy, and then paste it as a child of the object, (and do all the other tedious reapplications I need to do), and then the adjustment to the animation will show.

This makes no sense to me at all. Like, where and why is Unity caching the old animation?

If I to remove the clip from the importer, there will be no animation, so *That* will update. If I then add a clip to the importer, and apply, then put that into the animator controller, guess what happens?

THE OLD ANIMATION IS STILL PLAYED!!!

How is this even possible!?

I've tried generic rig... nope.
Generic, back to mecanim.... nope.

Is there no simple way to import updated animations?