Nuendo 12 on M2 BM ultrastudio monitor video playback frame skips


I have a Macbook pro M2 and use Nuendo 12. Love it!
But video playback with a Black Magic Ultrastudio monitor skips frames. I use the latest drivers 12.7 on Ventura 13.6
I use Prores LT files, with h264 it is even worse, lots of skips on 24p, 25p fps in HD 1920x1080.
On Media express (Black magic) it plays perfect, in Premiere also perfect.