I just ran into a raiden who looked like he could do an infinite chain grab. has anyone else had this issue? I dont have footage unfortunely, but it looked like he used his stun move (may be a command grab) that leaves you in a crumple state, then does a forward dash slash that nocks you down, and then uses the stun grab and repeats. It doesnt technically gain much meter (because the grabs only knock it out of you) but that also means you cant get out of it with the meter ceiling. This is something that needs to be checked out by someone who can record.
I tried this out in practice against a max level CPU. It doesn't seem to be infinite as the computer was able to roll/block however there were times when i was able to keep it going for a bit. This was assuming i was doing it right. Honestly, I does not appear to be a real issue unless you primarily play 1v1, in any other mode it is nothing to worry about. Also, once you get against a wall it stops working.