I have a docked floating toolbar with "Go DRIVEBUTTONS=cdrom,network,removeable,..." in a button. After installing 13.12 the button doesn't update and show a new drive when I insert it.
I haven't been installing all the betas, so I don't know exactly where along the line it stopped updating automatically. But it was working as expected in 13.11.
I doubt it's something that changed on our side recently.
What kind of drive is it?
Some drives do not properly send media insertion events, so nothing knows the change has happened. Showing the drive in File Explorer often then makes the operating system notice media has been inserted, which triggers a media change event to be broadcast, if that is what's happening.
If you have run the whole Opus process elevated (UAC), that will also block media insertion events from reaching it. See the FAQ on UAC for more detail about that, and how to use elevation without causing problems.