Why has the "Choose Layout..." preference option disappeared?
for me it hasn't
I believe this issue is present once you open BeepBox for the first time on your device.
If you are accessing BeepBox on your mobile device, layouts will be unavailable. Otherwise, unsure.
It is not available on mobile devices, or other devices with small screens.
For testing purposes, it's possible to configure a browser to simulate a small screen. If you do this while BeepBox was already open, the menu option's visibility wouldn't be updated, but I fixed that in: https://github.com/johnnesky/beepbox/commit/69f2602c43c3f853cfb377fe97d05a3e586f91e9