Dear Awhitefield,
This error could come because of
1. White host list is not updated proprly
2 Engine port is blocked at end user side
3. web sockets are blocked at end user side.
4. Any proxy server is block ports need by Qlik Sense
When applicable please mark the appropriate replies as LIKE. This will help community members and Qlik Employees know which discussions have already been addressed and have a possible known solution. Please mark threads as LIKE if the provided solution is helpful to the problem, but does not necessarily solve the indicated problem. You can mark multiple threads as LIKE if you feel additional info is useful to others.
Best,
Rohit
