Aparrently if you make 302 raids at once and you join one of them the raid icon still stays blue.

It stays blue only when you join a raid that is like 6 or 7 rows down from top one.

That's a performance shortcut I took. Basically, it stops bothering to look after 6-7 raids, and just shows "..." instead. I should be able to make it show the icon in the correct colour though, and possibly always show the raid you're in? I'll try that.