We developed several Nintex 2013 Workflows using People Picker function and they worked fine. Now the People Picker function is no longer working on all Site Collections except the Root for existing Workflows. The error message says "No Results" undefined; we have checked the Profiles and that is working fine. If I create a new Workflow, the People Picker works fine but it no longer works on any of my existing Workflows on all my Site Collections (except Root) as well as a separate Web App that was created.
Any ideas on what to do to fix this issue or what may have caused this? Any assistance greatly appreciated. Thanks.