Possible bug with Sub-Process

Question

A number of times now we have run into and issue where the output variables of the sub-process node no longer function for some instances of process model. The code/model is correct and functions 90% of the time but with no know pattern it will at times lose the output mapping. 
 This is the image of the output mapping under the setup tab of the sub process node. As you can see we expect to map createModifyProductOrderResponse to modifyOmResponse

Now the issue is that sometimes for single instances of the process model this happens 
 
 it has lost the mapping for that instance and a null is passed. This causes the process to fail later on when we need that variable. There are no code changes between these two screen shots and the top one is of the current published model. Also when we go to the edit the base model after we see this issue the mapping is still there as it was in the first screenshot. We can only see this issue when we have a failure and go to edit that individual instance. The sub process it self is functioning correctly and is populating the value as expected. we are currently running 16.3 with hotfix J

vijayd · Accepted Answer

This issue is there in Appian for a while. For a temporary fix, try to Save and Publish the process model. I have observed this issue when we change the name of variable after the mapping. Did you get a chance to raise a support case with Appian ?

Jamal Case · Answer

I ran into this issue as well. I just deleted the outputs and remapped them again and save and published the process model and that solved my problem.