replied on February 11, 2020
It's probably best that you contact your reseller and open a case with Tech Support.
As a round of preliminary investigation, you can take a look at the repository tab in the Subscriber Trace and see if there is an error listed there (if there is, it would a yellow warning sign in the top left graph). If no errors are listed, you can also see when the Subscriber last received notifications from the Laserfiche Server and connected to the Workflow Server. If those dates are fairly within 5 minutes or so, then the Subscriber is likely fine.
You can find more errors in the Errors node in the Workflow Admin Console.