Hey!
When using VCV Rack in Ableton Live with Live in fullscreen mode opening most plugins in a Host-FX module causes the plugin GUI to open up fullscreen.
Also when in DAW fullscreen mode you can load a VST plugin in a Host-FX module and it will display a ‘(no plugin)’ message on its display even thought one is loaded.
Also often loading a VST plugin in Host-FX will quit Live.
None of these things happen when not in DAW fullscreen.
An easy answer would be not to use fullscreen but thats the way I prefer to work, less distractions.
Cheers! Pat.