tl;dr: I think I've fixed the signature problem. BUT we can't have apostrophes or quotations marks in signatures on this board.
Ok, it's really fixed now.
But remember, no apostrophes or quotation marks. If you try, you'll get a message, "The page you are trying to access is restricted due to a security rule.".
Please let me know if you have problems with your sig (other than not being able to add apostrophes or quotation marks).
Shockingly, when 'Can add a signature' is disabled for a user group, people in that user group can't add a signature. I have no idea how that became disabled, but it's now been enabled.
I was trying to add a quote with an apostrophe in it to my sig and I kept getting an error message. I finally googled it, and it's true: we can't add apostrophes or quotation marks in signatures. I could get them enabled, but it would involve contacting our webhost and getting them to whitelist a few rules. Maybe if I ever have to contact them about something important, I'll throw this in there.
Ok, it's really fixed now.

Please let me know if you have problems with your sig (other than not being able to add apostrophes or quotation marks).
Shockingly, when 'Can add a signature' is disabled for a user group, people in that user group can't add a signature. I have no idea how that became disabled, but it's now been enabled.
I was trying to add a quote with an apostrophe in it to my sig and I kept getting an error message. I finally googled it, and it's true: we can't add apostrophes or quotation marks in signatures. I could get them enabled, but it would involve contacting our webhost and getting them to whitelist a few rules. Maybe if I ever have to contact them about something important, I'll throw this in there.

We can get better, because we are Not Dead Yet. -Frank Turner