Mr. Kevin: for the UBAQ i am using the JobStatus method and not the JobEntry.
My guess is when someone updates the JobHead.Character05 field the BPM (auto generated) does not change the JobFirm meaning it is off and for some reason it is writing that value to the job. Total guess on my part.
I just re-worked the BAQ to use a Calculated string and i called it Calculated_JobFirm so i am not including the JobHead.JobFirm field in the dataset at all. I tested and it seems to working fine. At least the jobs are not being “unfirmed” anymore.
What a mess 
I am tempted to go into Pilot to test this out and offer support a repeatable scenario. However, since i have worked around it - i do not see any benefit to me.
I created a mess in our Live system becuase of an Epicor “Bug”. Epicor is not going to fix our mess - we will just have to deal with the 17 jobs that got unfirmed.
I added this info hear to warn any future users of the JobStatus method - DO NOT include the JobHead.JobFirm field in your dataset - create a calculted field instead.
DaveO