Can't register account in game

Just to confirm all of the following...

• The game was installed via Origin, Steam, or GOG. The disc version and other versions of the game will not allow you to register or login, those specific versions have been discontinued, but the other three are actively supported.
• Spore is listed under My Game Library in Origin. If you have the Origin app installed, click on Spore, click the gear, Game Properties, and verify that a CD key is listed. This key must be present before you are allowed to register, as the Spore server will check for it.
• If you've only recently registered Spore on Origin, sometimes it can take a few hours before it updates on the Spore server
• You can login to Spore.com and it shows the email address at the top.
• You are registering through the form at the bottom of the registration screen in-game, by entering your EA/Origin email address, password, and a new screen name for Spore.
• Your email, password, and new screen name do not contain special characters, and are under 16 characters long.

If that's all correct, I'm looking into if this could be a server issue.

The server appears to be correctly identifying accounts that don't exist, and that already have a Spore persona registered, so it's clear that the registration form isn't broken entirely. If I have any other findings I'll post back.