Prior to the latest SW upgrade the enter key on the remote
moved the PIP window as you described.
This functionality was broken aboiut 1/2 way through the beta test for the latest version. It was reported as a bug but the problem was not corrected before the SW was released. I think the bug report was simply closed with a comment to the effect that the RCA unit didn't exhibit this behavior.
The functionality is missed by those of us who used to use it.