New library not finding files

[splendidgeryon]

I just imported my iTunes library into MusicBee, opting to leave all files in their current locations on an external hard drive (I will continue to use iTunes to manage my other devices, but want to use MusicBee on some computers).

Now every track requires me to "Locate" the file--even though it shows me the file location in the popup window warning me it can't be found. 

Any ideas on how to help MusicBee find the files, without copying everything to a new location (and thus doubling my already very large library)?