Hello, we currently also have an issue with all actions who needs users/groups. (On some Sitecolletion not on all, to make it easier to identify an problem)

Can you add an new "Assign a task" action to the workflow, and the most imported question, are you able to do an configuration?

If the problem persists, it might be a good idea (as shown by the error), to contact the Nintex support

Alicia, were you able to resolve this issue? I am having the same issue, and despite several attempts to pinpoint the problem, I have been unsuccessful. Thanks!

Hi Rachel.

The error was because the workflow was failing, the variable that I had in the assign to field was empty. When I fixed the workflow issue everything worked fine.

Hope this can help you.

Regards,

Hi Alicia. I was receiving this error without the workflow being suspended, so there weren't many clues! I could narrow it down to happening with one specific task form (which I had imported from another site's workflow and had re-linked to the current site list). I scrubbed every detail in the form, and it turns out there was an ampersand (a.k.a. the character devil) in a control label. Removing the ampersand fixed the error!

Thanks for following up!
Rachel