Same behaviour for me but my item is updated via PowerShell.

I found a workaround which works for me. Check this post: https://community.nintex.com/message/3512#3512

This is an issue and I have been reporting it to Nintex for 2 years.  In early 2015, I managed to work with the right people who were able to repeat the issue, which is the issue where the workflow hangs and never progresses forward even though the Wait for Item Update criteria has been met.  In my findings while working with Nintex to reproduce the issue, the problem was repeated by Nintex, and they agreed that there was truly an issue, and it was their assertion that it was a problem with Microsoft SharePoint backend functionality.

The problem explained to me was that they had to be able to re-create the same situation using SharePoint Designer to prove to Microsoft that there exists an issue.  Unfortunately, at that time Nintex was unable to re-create the problem using SharePoint Designer.

Whether this issue gets resolved, I know not, but it is definitely an issue that Nintex has seen and have been able to reproduce using their tools.

I have a feeling this is Timer Service related.  Are you able to restart your timer service and see if that moves the workflow along?

cheers,

Vadim

Check the eventreceivers on the list where the workflow runs (see here for more info on this). Cleaning out these solved it for me. Seems they are interfering with each other in some way.

I had some other issues as well and again, duplicate eventreceivers were the cause of all the problems. I'm still not sure how those duplicates are getting created though. But it happened at some point.

Hope it helps.