Unable to move a folder from C: to an external folder in LRC

To free up space on my internal drive, I all of my international travel folders to an external drive.  This was quite a while ago and I've never had any problems accessing them

But today (several upgrades to LRC later), I tried to move another folder on my internal and could not.

I should be able to drag/drop....yes?

When I do that, I'm unable to drop it on the drive name OR as a new folder on that drive.

So, I created a folder on the external (outside of LR) with the same folder name figuring I'd drag/drop all of the subfolders into that one.  But that new folder isn't showing up on as a folder in LR.

I'm stuck. 

I can think of some workarounds, but this SHOULD work.  And, since I'm told repeatedly to organize my photo files from inside of LRC, that's what I'm tryin' to do!