Never mind, I'm an idiot. YES, my network drive is mapped and has been since shortly after I got this computer. HOWEVER, apparently I installed Calibre BEFORE I mapped the drive and Calibre was pointing to the networked drive and not the mapped network drive.
It never occurred to me to check that because the drive was mapped. All problems solved.
But in answer to your question, yes the only thing that didn't work was the open containing folder option (and every variation of this).
By the way, I know hitting the O key worked before on this computer so apparently with older versions of Calibre, it wasn't necessary that the drive be mapped.