For some reason the site always redirects me to .co.uk when I'm in the forums. So I can't test that possibility.
As for Best Answers, I know I had some as of a month+ ago, can't remember the number, but I actually saw the number on my profile status page, for a couple sections. Now that profile page shows no best answers anywhere.
Also, I'm noticing the "threads" tab in the right-hand isn't showing me new answers to threads I've answered in. I'm relying on email notifications only (which doesn't actually notify me 100% of the time). Hmmm...
This all started yesterday/today. Before no problems. *scratches head*
Your initial thought was exactly it - UK vs Global!!
However I'm still baffled. Everytime I typed the URL to .com yesterday, or clicked Global-Tom links (sent to homepage) and clicked Forum I was auto-redirected to the UK. However, your link above "semi-fixed" the issue as I suddenly saw the thread tab on the right. So I started clicking account links, and after a couple of clicks I was redirected to .co.uk. Now I can manually change it to .com in place mostly with success, but anytime I click, it redirects me to .co.uk.
I didn't think it mattered that much. But now seeing it, I'd prefer to lock it on Worldwide.
Do you or anyone else know how to force my forum preferences to Worldwide? I've looked all over my profile and the forum main page and can't find anything. Maybe I need to hunt the cookie down and hack it... :-/ Or as usual the setting is right under my nose...
*still scratching head*
EDIT: I can put .com in place on the forum categories page and profile pages. Nowhere else.