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!

Hi Andrew

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.