Symptoms

workflow error starting and IPC event for several destination users.

I have started an IPC workflow however the activity is preformed 3 times, for 3 users, but a child workflow is created for only one user.
the document contains screenshots of the view flow and the error message in the log file which is stoping the child workflows from being created.
 

Diagnoses

The first IPC Child process gets started
However the second and third IPC event go into
"Sub Process unavailable" state/error
 

Resolution

Since you are using an Asynchronous IPC Event with multiple slots, you need to make all of the slots are complete prior to the Activity completing to ensure all of the child processes get started. You can do this by adding a Succeeding Rule to the Activity containing the IPC Event that looks like this:

All of oActivityInstanceDestStatus] = Completed