Going back to the form with a session shows empty fields

I followed the instructions on how to make a "save-able" form. By creating a form and then creating an "Intro Form" where the user creates their first name and email to use as a password to log back into the form and complete it at a later time.

Problem is this didn't work. 

When I've done this in "tests", it's worked. We've used real emails and managed to go back in no problem. Now however, when I check back, nothing is there. I didn't accidentally hit submit, and I definitely clicked "next" to ensure the data was saved. What is happening?

Based on what you have mentioned, you were following the steps shown here: How to Save Forms to Continue Later

Now this uses email sessions on the form, but seeing how we had some issues today it is possible that the sessions data got removed or temporarily unavailable.

Having that said, you should still be able to use the sessions and they should be working from now on, but please do note also that sometimes - if you have auto-fill option turned on as well, the values of empty fields could be remembered and as the values are added, they get removed as well.

This is not something that usually happens, but it did happen on few occasions where forms were long and auto-fill option set to low timeframes.

If the sessions got temporarily removed, it might take a few more hours before all sessions are restored back, so do feel free to check it out a bit later if it is not working for you at this time and as mentioned any new sessions should be OK.

I also suggest checking with people that did tests with you as well since they could have submitted it later on - and I say this only since I did not see any such issue with the email sessions so far.