I have multiple sites using Gravity Forms on the same server (yes, I still have to upgrade to developer license). All of them worked fine until a few days ago. Notifications are not being sent and I can't figure out why. It's not an issue with 1.3.10, because one of my sites is still on 1.3.9 and it has the same issue. I didn't make any adjustments to my themes or plugins, so it's probably an issue with my hosting provider.
I also tried installing Gravity Forms on a clean WordPress with default theme and no other plugins.
Any idea what could be causing this?