I've had this problem before but can't remember what I need to check in Preferences (or wherever). I've searched my posts but the message is nowhere to be found.
 
I insert a loop into the timeline (audio). Nothing but dots appear. The solution was to check something somewhere (or uncheck) to solve this problem. Can someone refresh my memory? Thanks a lot. 

check for import broadcast wavs

That's it. Thanks a lot, markyzno.