@andrewsober – unmerge all cells in the row "Albany Downtown".
Now you can copy/paste the columns. Merge the cells in the row again.
It could be a "bug" or a (missing) "feature":
as long as there are merged cells in a row like that, you cannot paste the column from the clipboard.
@Laubender, Thank you! That did the trick. I knew I was missing something. You're the best!
@Andrew – btw. this problem is not restricted to InDesign CS6.
I think all versions are affected, though could not test in InDesign CC.
So you could mark my answer #1 as "correct"…