I seem to have the same problem. I’m running Ubuntu 21.04. I worked around the problem by unplugging the second monitor, starting the editor, then plugging it back in once the editor was up. Once the editor is up and the second mon it is plugged back in, everything seems fine. The Graphics card in my case is an NVIDIA 1660 ti. I’ve seen the behavior on 4.26.2 and 4.27.