I installed this enablegfpaymentdetails plugin but it appears that it was a bit outdated. I am unable to see any of my gravity forms now and none of the menus work. I tried changing the theme and deactivating other plugins but nothing is working. I already deactivated and deleted that other plugin that I think caused this. The forms are using SSL. The site is https://snuginconline.org/conference-registration/
I recommend opening a support ticket so that Gravity Forms support can help you with that: