A nintex form I was architecting in O365 has stopped loading. I can navigate to the design workspace but the loading icon spins indefinitely. I've tried refreshing my browser, cache, and using a new browser. I've also opened the console to see if an error shows up but no errors appear. The form will load when it is run.
As Fernando suggested, exporting and importing over to another list will help us to see if there is a wider issue with that particular design.
I recommend reaching out to our Support team at firstname.lastname@example.org if you continue to face issues.
Any service related incidents will be posted to our status page: Nintex Services
Can you confirm what type of form design you are utilising? Responsive or Classic?