It may of course be down to some gate agents simply not knowing what they can/are allowed to do. I just didn't get that impression as she talked to someone several times.

I once tried it in Go at CPH arguing that the only reason I was not booked on the earlier flight was that the MCT was not long enough so it was not possible to book it. That did not work either and the gate agent told me that they are/were allowed to do it on all Plus tickets and for EBPs. EBG and EBD does not help. That was probably a little over two years ago.