Libraries empty in Dopus but not File Explorer

I have some libraries on a USB drive. Sometimes I forget to turn on the drive before booting the PC. If I subsequently turn the drive on, Opus will tell me that the libraries are empty, but File Explorer shows the correct contects

Windows normally blocks adding removable drives to libraries, so it isn't something we ever aimed to support.

But what happens if you use File > Exit Directory Opus and then restart Opus?