Imported h.265 8k messed up

First time i encounter this problem.

Working with h.265 8k 29,97 video.
Original media outside of premiere looks fine.
When imported in Premiere Video is messed up. Jumps in the middle of the clip back to the start or stuttering, jumping.
Proxies look fine. When switching between proxies und original - they are not in sync. Export confirms, it only exports messed up video.
Encoder also only grabs the messed up video when trying to encode otherwise.