Hoping that someone can answer this question(s):
How many State Machines can you have in a workflow?
If there is a certain number of State Machines that can not be exceeded what are some of the issues that can arise?
What is the best way to troubleshoot issues with State Machines?
Thank you for your reply on this question. No I had not looked in the two areas that you have referenced.
In doing a bit of reading, I did have a Change State Machine object at the end of all State Machine "flows", but on one of them I did have the End Workflow object. I now believe that this might have been the reason for the issues that I was having with trying to publish my workflow.
In this case I have decided to go the long route and recreate my workflow to reduce errors and hopefully other issues.
if Franks answer helped you, please mark it as corect so other users can see there is a solution for your question.
Thanks in advance
p.s.: Since Workflow created with nintex are regular SharePoint 2010 Workflows the same thresholds apply (see: Software boundaries and limits for SharePoint 2013 )