workaround: 8va in tab
Edit (18 July 2022):
Here is my current workaround for this problem.
I have included a musescore file and an mpal file.
Feel free to use them as I do not have faith the problem will be fixed.
The method is still the same:
Place an invisible 8 or 15 octave clef.
Add a line which does nothing to playback; make it invisible in TAB.
I no longer use 12pt italic, using symbol syntax instead.
I haven't searched for this today, but I was excited by this.
If someone alreay posted this workaround, I apologize.
I have discovered a semi-convenient workaround for 8va lines wrongly appearing in linked tab staff.
Insert clef +/- 8 or 15 as needed; make it invisible.
Generate a generic line that does nothing to playback; make it dashed; make it invisible on tab staff.
Generate 8 or 8va in bold italic 12 pt staff text.
My last wish would be a palette item, a 8va hooked dashed line that tracks with notes, but does nothing to playback. This would make inserting this faux 8va line a little easier.