Remove Duplicates - Weird Behavior

I have one column with 200 lines of data in it.  Let's call it range P33:P232.  I want to remove all the duplicates in that data but keep the original data where it is, so I copy that range and paste it (as values) to cell DD18, then remove duplicates there.

Here's the problem.  I verified using a column filter on the original data that there are twelve unique values in the data.  When I run the remove duplicates function, it says that twelve unique values remain, but I see only five of them, with no sign of the other seven values.

Now if I copy that same data range to CQ1, the remove duplicates command works properly and I see all twelve unique values.

Can anyone tell me what's happening here?  It makes no difference whether I paste with Ctrl+v or right-click-paste as values.

I'm sorry I can't provide a workbook example of this right now - needs some scrubbing before I can post it.