Check Your Signatures - Options

[Talls]

Figured out that they no longer allow [a] tags for URLs, and use [URL] instead (which it automatically uses when you used the link button), and you can't apply css styles to it unfortunately. Thats another place to look.

If you notice you're using [a] tags for your links to your player page for example when checking your sig, delete those fully and just link the pages using the link button, and it should resolve those issues

EDIT - JK I'm not fully correct, there is a way to make it work with [a] tags, but if it isn't exactly correct then your sig will just disappear like a fart in the wind

You should be able to use [a] tags now.  Made sure to fix that too.