Tablature doesn't like unisons and/or large spans between frets

When I try to drag tab numbers to other strings to make unisons, MuseScore rebels.

When I create two open notes, open E 1st string and open B second string, for example; and then select the B-string tab number and Shift-arrow up in an attempt to produce an open 1st E and a 5th fret 2nd E (unison Es) the tab number for the second string increases up to four, and then both tab numbers jump to a lower string when I try to make a tab number greater than "4" This only happens when there are more than one string with tab numbers on them.

I assume this has something to do with the way MuseScore guesses fret positions for chords when notes are copied from a notation staff, or possibly a parameter to guard against unreasonable or impossible spans between frets, but it takes away the possibility of open voicings (chords up the neck which use open strings as well).

This is an important capability for modern and even classical guitar tablature.