
I’ve seen this as well a few times. From what I’ve observed (and assume), lookups and reference group controls are not fully supported in PFE yet, which is why you see UI glitches like resizing on focus and plain (unstyled) lookups. The workaround I used was to disable the lookup on the reference group and instead open a separate dialog form. I added a small image/icon next to the control, and on click, it opens the dialog. This also works well on tablets. I agree this can be a bit of overhead if there are many such controls, but sharing it here in case it helps someone.