Theme changes don't work correctly after opening the About box

Windows Terminal version

1.12.3472.0

Windows build number

10.0.19041.1415

Other Software

No response

Steps to reproduce

1. Start Windows Terminal (don't just use an existing session).
2. Open the Settings UI, and go to the Appearance section.
3. Set the Theme to Light, and click Save.
4. Without closing the settings, open the About box, and close it again.
5. Now switch the Theme to Dark, and click Save.

Expected Behavior

The UI colors should change to the dark theme.

Actual Behavior

Most of the UI remains using the light theme, but some elements appear to be updated in such a way that they become invisible.

This breaks in a similar way when switching from dark to light, and it's also not only the About box that triggers it - I think any popup dialog will do (e.g. the "Do you want to close all tabs?" warning has the same effect).

If you open the About box again, it temporarily "fixes" the problem (i.e. it refreshes the colors correctly), but that only last until you try and change the theme again.