Yep, already did rule these things out — it also doesn't happen in Ubuntu 18.04 or Windows, only on Ubuntu 19.04. My guess is that this is a kernel or GPU driv

Yep, already did rule these things out — it also doesn't happen in Ubuntu 18.04 or Windows, only on Ubuntu 19.04. My guess is that this is a kernel or GPU driver issue, since it doesn't happen in Ubuntu 18.04, but it will take time to find exactly which version of the kernel get this to stop.