I am converting all the posts from Classic, and making several text changes to each as well:
* From post view, click top menu edit post
* Switch to block editor\Click anything in the first block to render convert to blocks menu
* Click convert to blocks
* Make changes and update

The conversion happens, and changes are saved, but the post still shows as Classic Editor in the post listing. When you click the top menu edit page button from the view page, it opens the Classic editor. Was working fine up until yesterday, I’d done about 20 posts with no issues.