I understand, but it often happens that the exact same symptoms end up being different causes. We cannot know until there’s a solution. It’s best for everyone to keep their issues separate or things get confusing fast. I know how tempting it is to want to jump in with a “me too!” and that it’s even preferred in other forums. If readers want to follow along because they think they have the same issue, that’s fine. Even contributing with “have you tried…” is fine. Just don’t confuse an OP’s thread by posting one’s own issues and hoping for someone to help with that.
I’m sorry I can’t offer a sure solution. It’s odd that there is no error message or anything giving a hint to the problem. The only problem I’ve ever had was time out issues. The update script is supposed to alter the time allowed, but I’ve found I had to add set_time_limit(300);
to wp-config.php to solve the problem. Depending on one’s server configuration, this may have no effect. May be worth a try? I wouldn’t hold out much hope though. I don’t think that’s the problem. Clear your browser’s cache and your site’s cookies after trying any change.
Apologies if you’ve answered the following, I didn’t read through very carefully. Do you have any caching or security in place on the server, either through WP or your host? Any of these could cause problems. Disable any of these that are in place for the update, they can be restored afterwards.
At some point you may need to give up on finding a solution and do a manual update. It’s possible subsequent updates will work fine after this, it may be a one time quirk.