It works actually (deals damage and appears in debuff tracking addons). It causes desync which is only visual problem but it is hard to get used to it.
I solved this by changing my rotation and always bar swaping after Degeneration. But that's only a workaround and real fix is needed here.
Any other skills with similar issues to give the Devs best chance of identifying / fixing the issue?
Daedric Prey, Ice Comet (ulti). Sweeps is wacky. Just test a MagSorc or MagPlar and work your way through a rotation. The de-sync/delay issues are obvious.