Thanks for the help!

Welp, that explains a lot...

Your levels are tied to your xp, which comes from statistics on your submissions. If one of your submissions is deleted, drafted, or disabled, you lose all xp that the submission gave you (at least until it is restored). Sometimes your level may take a while to update to reflect the loss of xp, with certain actions triggering it to update sooner that it would otherwise.


What was the last thing on your page?

Did you publish your submissions live?

Your levels probably disappeared because of either your submissions being removed by a mod or you accidentally removing them, seeing as you have none. If you remove submissions that gave you levels, the levels disappear with it.