Posting this here because ROBLOX Support was no use whatsoever.
Currently, when trying to animate R6 Rigs using the studio Animation Editor, keyframes do not show up, nor do the active body parts. However, your animation will still play, but it is impossible to make anything more than one movement, given you cannot see or adjust any keyframes.
Hoping this gets fixed ASAP, because it is impossible to work on scripts or other things that require animations when using an R6 Rig.
Literally minutes after making this I found a post that has the solution to this.
Go to the rig your trying to animate, find the “PrimaryPart” property and change it back to the humanoid root part by either selecting it in the explorer list or just clicking on the dummy.
A recent update seems to have changed the PrimaryPart to the head, not sure why, but thankfully it’s an easy fix.
Credit: Keyframes not appearing in animation editor - #5 by superhomer64
Thank you so much, I was not able to animate an couldn’t finish my things because of this, I will try what you suggested and I wish it work, thank for making this VERY helpful post. 
Houra !! That worked so fine, again thank you very much.
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