Moving breath marks leads to strange measure stretching effects (MuseScore 3).

OK, this is a bug report as well as a feature request:
For choral literature with 2 voices in one staff you often need breath marks at different places for both voices. Since breath marks can only be attached to the first voice of a staff, I have always moved them to fit the 2nd voice. This is often possible, but sometimes both voices are rhythmically too different.
If you move a breath mark in MuseScore 3, the automatic placement shifts several notes and unintentional stretching occurs in the affected measure. If you deactivate the automatic placement for the breath mark, it will still affect other elements. Actually, it should be ignored by them. If you want to place the breath mark more precisely over the inspector instead of using the mouse, the breath mark will always move the next note further back. If you reduce the X-value again, it still moves in the wrong direction. Undo also doesn't work properly here and resetting the X/Y values to 0 doesn't always work either. Well, maybe that was too vague now.
Example procedure (1st case see file in attachment):
1) Placed a breath mark behind the eighth note (syllable "e") in the first voice.
2) To use it for the half note in the 2nd voice, move it down (Y) so that it rests on the last line of the staff.
3) Move it to the right (X) to place it in front of the next quarter note ("for").
4) The further it is moved to the right, the more the measure is stretched (IMHO too extreme). If you want to engage reverse gear, it first stretches the measure even further until it moves back at negative X-values. The stretching remains partially. A reset from X+Y to 0 does not bring you back to the starting point. Undo does not work as it should in this case.

Basically it would make sense to anchor breath marks, dynamics, lines etc. directly to the respective voice. If you have too few anchor points (notes) and need breath marks for both voices, you cannot add two breath marks to a single note to use one for the 2nd voice (2nd case, mscz file). Alternatively, a breath mark from another measure would have to be moved there, or a breath mark would have to be inserted as text. This is easier to move and does not lead to such stretching effects. But this is all fiddly and just a workaround.