local files can't be played or queued; no error message displayed

[Tim02130]

Plan: Premium

Country: USA

Device MacBook Pro 2009

Operating System: MacOSX 10.10.5

My Question or Issue:

Just installed Spotify's Desktop app, added a folder to the local files list, and while all the mp3 files there are displayed, largely with the correct Album, Artist etc. info, nothing happens when I click the "play" icon on the left, nor when I right-click "..." and select "Add to Queue" (nor are the files currently in the queue affected by any of these operations). No error messages pop up, nothing appears in the system log, and an internet search does not reveal any recent instances of this problem either.

Any ideas anyone?