A mandatory constraint to generate unique record in ZX_LINES_DET_FACTORS is violated with error code

Hi,

The Invoice Validation program in one of our Operating Units in R12 AP is encountering the above error message for several successive days now. I looked up the Unique indexes of ZX_LINES_DET_FACTORS and found ICX_SESSION_ID is among the indexed column. All of the rows in ZX_LINES_DET_FACTORS table have null ICX_SESSION_ID.

Is the null ICX_SESSION_ID causing the "constraint..." error above?   What can we do to avoid the null ICX_SESSION_ID column?  Can we pre-populate it with some default value?

Where does Oracle use the records in ZX_LINES_DET_FACTORS?  Can we delete them so we can run our Invoice Validation program without error?