I tried deleting all the SDKs and re-downloading them, no change, still can't submit for review.

Yup, same here, I'm guessing it is some problem related to the connect website than some problem with our installations of Xcode + SDK

I received 2 e-mails today. One earlier today in an account that hasn't really been active since 2014 or so, which had me scratching my had for a bit earlier today, and one just now, on our actual dev account, which has us pretty worried. So the error is still happening it seems. If this e-mail was sent in error, can you send a follow up e-mail about it being an error or something? Also can you stop the error? It seems to me e-mails are still being sent out.

Did you ever find a solution? In our tests, we haven't be able to make isVisible return true either. Not sure if it's not working or if there's a problem in our understanding on how it's supposed to work.