Nintex New Responsive Form Crashing with "Something isn't right" error during stress testing

We have a tool built for call center agents that serves as a knowledge management tool.  Based on the input in 3 - 4 drop down boxes, the remainder of the form is loaded using lookups to populate relevant information for the agent to assist with the call.  The source for the form is SharePoint lists (several lists with values retrieved using the lookup function).  While testing yesterday with 5 users simultaneously, they all started receiving the error, “Something isn’t right”.  Has anyone else experienced this type of issue?