Cannot attach existing disk. Can only create empty?

I created a data disk to attach to my development VM (Win 2012).  I then had a need to create a new VM (Win 2008 R2) and tried to attach the data disk to the new VM after detaching it from the older VM.  Now, I cannot attach this disk to either VM.

List of all VHDs - 

Click Attach on my 2012 VHD - 

Click Attach on my 2008 VHD - 

I am at a loss here.  I don't want to delete the VHD as I already have data on it.  I just want to re-attach it to my 2012 environment and maybe attach it to a 2012-R2 environment when I decide to upgrade to the newer OS.  When I run my Dev VM and log in, disk manager does *NOT* show any drives attached.

Any thoughts??  Suggestions?