Hit "B". It looks like you may have soft select on.

I just joined this site. Did you ever figure out what the issue was?
I figure you need to set the painting to "add" as it's probably on "replace".

I've been an animator for a few years now and I've run into this issue once before and can't remember what the fix is and I can't find it anywhere.
The issue is that the foot roll attribute in the...