Andrew Beals your blog post When publishing a workflow you receive the error "soaperverServer 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!