Elder Maven witched bosses just standing htere, and not going to different phases

Was doing the elder bosses with maven witnessed, and the bosses would not phase, they would just sit there and not move from initially spawning. Happened on two different bosses.

Multiple threads for the same issue. 1 of 2 usual cases:

1. Too much damage. Only relevant for spawning the additional bosses via Destructive Play. The bosses will phase like normal.
2. Maven + Elder + Delirium appears to be the cause of non-phasing Elder bosses. Remove Delirium, problem solved until they patch it.

I've done over 100 Elder maps this league. Have not had a single boss that did not phase. But I don't run Delirium.