Hi - Thanks for the reply!
Yeah drivers are current but it does appear that a system reboot alleviated the problem. Possibly the GPU had gotten into a funky state and just needed something cleared. On the bad runs I was also getting log warnings about long wait times for PSO’s.
On a post-reboot test artifacts are no longer present, and frame is taking a very reasonable 29ms to render in the starting view. Log warnings about the pipeline state objects are no longer appearing.