Another issue in 23.2.1 on windows and RTX GPUs. This worked fine in older versions. Mattes are strobing when pulled in Primatte.
I have sent a request to Maxon also.
After Effects 23.2.1
Windows pro 10.0, build 19045
Ryzen 9 5950X
128 RAM
2xRTX 3090 (Latest studio driver)