@leenab Do you remember which plugin created the problem?
You mean the wp-admin folder? I did that already by ‘re-installing’ from the updates page.
UPDATE: I was able to temporarily find a workaround for the image upload issue. Right clicking and opening the links in a new tab helps. That said the problem with WYSIWYG editor remains.
Just tried it, didn’t work.
I deactivated all my plugins, but the problem still persists. Any other suggestion?