I just tried an installation of the latest 4.1 version from scratch on a completely new disk. The installation process went flawless but once Qubes OS booted, I tried to add a new panel (as a dock). When I attempted to change the background of the panel to an image, both panels just disappeared suddenly and the panel configuration tool would also fail every time from that point forward, with a gnome error. I tried creating a new user to have a completely clean /home for that user, but the panel wouldn’t work on the new user either. Unfortunately, it was easier for me to just reinstall from scratch again rather than troubleshoot the issue, but I wanted to report the problem here, in case someone ends up having the same problem.