Custom template shoots Appearance settings - bug

Given:
- select a plugin template in "Settings > Appearance" (like Full-Width...)
- then copy the correct template file to your own theme-child and modify

Result:
- works as it should. I'm happy.

Then:
- visit again the Events Settings page: "Appearance" tab is missing.
- change anything anywhere and save Settings

Result:
- Events Appearance settings are deleted (guess as the tab wasn't present when saving)
- Events shows default (no selected) template, thus ignoring custom template

Work-around:
1. rename custom template files so they are ignored
2. (reload dashboard and) make whatever event settings AND correct Appearance choice
3. rename custom template files to correct name

The problem:
The Events Settings have an issue with custom templates.
I do understand the idea of disabling the Appearance tab when custom templates are present in the current theme but the bug here lies in the issue the Appearance settings are saved as "none" (cleared) when saving the Events Settings instead of keeping whatever current Appearance settings are set.
I recommend to at least fix this "clearing of Appearance settings" and preferably rethink the Appearance / custom template handling.