Delete everything from the Picture Cache folder. These are all the pictures of the computed wave forms.
They will all be recreated upon file loads.
 
That should fix you up.

Ok, here's my typical reply after I've sought help from you guys. The problem has mysteriously disappeared (for the moment) without my having done anything yet. I tried it in a project with just one track, and one with 25 tracks and it worked. This was with the BlueTube.
For clarification, I have a single soundcard with 10 in/10 out. When I use a particular device, say the bBlueTube, I have 3/4 selected and the others disabled. Likewise, when I use the POD I have 7/8 enabled, and the others disabled. Everything goes out by way of outputs 1/2.
I'm a little perplexed. I do know that everytime recently that I've asked for help on this forum the problem has fixed itself automatically. So......who's the magician?

Oh, and one last clarification: ASIO never works well on my system, so I use WDM which as always served me well.
 

ChristopherM, this is for you:

dana martin
ChristopherM, this is for you:

Well, thanks for that! The taste must be very special, because its looks are not obviously those of a gustatory delight.