Featured image not appearing (not possible to select)

Yes sure, WP login in private information. Thanks a lot!

I tried logging in and opening a Post and a Page. On edit, I was able to locate the Featured Image Metabox in either. See: https://share.getcloudapp.com/ApuDGEdQ

Can you try using a different Browser? If that doesn't work, try using a different device.

Incredible that I did not test in Incognito. Thanks a lot!!

You're welcome Knuth!