Fretboard diagrams do not remain attached to staff at the correct location
See attached MuseScore file, fretboard_issues:
(1) Drag a fretboard diagram from the palette to the first note of the second bar, in the staff marked "vibes." Now deselect, then click and drag the fretboard. You will see that the dotted attachment line has shifted position and the fretboard diagram is no longer attached to the original note. If you repeat this operation in subsequent bars the fretboard diagram will even appear to attach itself to another system altogether rather than the note originally selected.
I have been reliably informed on the support forum that this does not happen to all files, so there is something about this score that causes the bug.