Check configuration never completes 2023.6.2

I’ve been trying to upgrade from 5.4, but when I do I receive notices of deprecated platform problems.
When I tidy up my configuration yaml, by removing the platforms, the Check Configuration in the Devloper Tools never completes.

I am too afraid to restart anyway. I just restore 5.4

I have a green tick after I save my yaml changes and the outboard yaml checker says it is valid.

Do I bite the bullet and retart?

Thanks