UNDO bug affecting customised text

Windows 7/10, MS 2.2.1, 51b8386

If you add customised text to a score, change the style, then UNDO the change, MS does not restore the custom text properties.

1. Create a new score consisting of just a treble staff.
2. In Style > Text > Staff, set (font) Size to 40.
3. Create some staff text.
4. Using "Text properties", change the font size to 12.
5. Save this in a palette.
6. Select an empty measure and double click this custom text on to the score.
7. Change the style using the Inspector's drop-down list.
8. UNDO.

Expected result: The (font) Size returns to the customised value of 12.
Actual result: The font-size changes to the size set by the "Staff" style for the score.