Negate Magic Ultimate is Freezing up since Imperial City Patch

OMA

I ran 2 of the large group dungeons today, Atherian Archives and HRC. I had negate magic on my ultimate bar and every time without fail that I threw down that ultimate , Absorption Field morph, the game would freeze up, black screen, spinning wheel of no response, right in the middle of boss battle. Yes there were lots of other ultimate s at the time. After I changed that ultimate out to something else like the Atronoch, then there was no freezing or stalling. Please fix?