Following the same process as before - uninstalling the hub, deleting the folders and downloading the new launcher, I ran the installer.
Entering a flight and selecting the G600, it now correctly opens on one of my G1000 panels.
Alt-tab reveals that the "stuck screen" is still there, now showing "launching avionics" with the sliding green bar.
This window is providing the black background to the G600 display and if the window is closed, my desktop shows through top and bottom.
The PFD side of the G600 seems to work OK, but charts/select does not allow selection of any airport other than the default KMYF
(FYI the launcher folder shows FSBLauncher-0.0.217.197 with the FSBLauncher.exe file dated21/01/2026 15:34)