Andrew Beals your blog post When publishing a workflow you receive the error "soap:ServerServer was unable to process request." resolved this issue. I saw it before I posted this but didn't run through it as my log entries weren't similar. But Nintex Support suggested a problem with Forms too so I ran through it and it resolved the issue! Thank you so much!
Woot! Nailed it!
The error messages may have changed since I originally posted that a year ago. I would be curious to see what the errors in the logs are now.
Great to hear its still relevant after all that time!
Thanks for your post. I am having similar kind of issue, it only happens when I am using Assign Flexi task and other similar task, however it works fine for Send notification and few other field.