H.264 Displaying very wierd in timeline.

Just updated Premiere Pro to 24.4.0 BETA (Build 21) And now suddenly all H.264 files are not displaying or rendering properly. They have a kind of purpulish hue and a lot of digital noise. ProRes and other file types look fine. Files play fine in VLC and Quicktime, rencoding to ProRes in Shutter encoder and importing into premiere is working as a workaround.

MacOS 14 14.2.1

iMac Pro

Intel Xeon W-2191B

128 GB DDR4