When system starts with a small-sized staff, the text-line thickness is wrong in staves below

OS: Windows 10 (10.0), Arch.: x86_64, MuseScore version (64-bit): 3.6.2.548021803, revision: 3224f34

1. Open the attached MS file. Note the small-sized staff in the top line (used for ossias).
2. In the Advanced palettes, open "Lines" and apply the "Staff line" (see below) to any note in the normal-sized staff:
   
   Expected result: The "Line thickness" reads 0.15 sp in the Inspector.
   Actual result: The Line thickness reads 0.1 in the Inspector (wrong).
3. Click on the Line thickness "Reset to style default" button (or just set the value to 0.15 sp.).
   Expected / Actual result: The line thickness resets to 0.15 sp.
4. Save the file, close then reopen.
   Expected result: The line thickness is still 0.15 sp.
   Actual result: The line thickness has reverted to 0.1 sp.
5. Set the line thickness to any value except 0.15 sp. Save, close and reopen the file.
   Expected / Actual result: The line thickness is saved correctly.

The presence of the small-sized staff prevents the user from applying text-lines of the normal default thickness (0.15 sp.) to other staves in the system. Remove the small staff, or move it to the bottom of the system, and the text-line thickness behaves as expected.