4x-dev: "Update score" window opens even if file was already updated in 3.6.2; changes are applied even if "Keep old style" specified

OS: Linux Mint 20.1, Arch.: x86_64, MuseScore version (64-bit): 4.0.0-1552514374, revision: 28863c6

Open the attached test file.

Bug 1: The score style was already updated in MS3, but, despite this, 4x-dev still displays the "Would you like to try our improved score style" window.

Bug 2: if you choose not to "update" the (already-updated in 3.6.2) file, the program reverts many of the text styles to "free serif" and resets their font-sizes as well.

Bug 3: If you close the window using the X icon (or F4), without pressing any selection buttons, the program reports an error (In MS3, the window closes and the score stays unchanged).