Journal Import (initiated from AP Transfer Journal Entries to GL) is not transferring attributes 1-1

I am using the GL_IMPORT_HOOK_PKG.pre_module_hook to update values in the gl_interface (actually updating both XLA_GLT_XXX, then updating GL_INTERFACE based on the contents of XLA_GLT_XXX)

I have turned on GL: Archive Journal Import Data so I can review the contents after I create AP, validate AP, create accounting, then run Transfer Journal Entries to GL.

I can see in the GL_INTERFACE_HISTORY table that I am successfully updating the value in ATTRIBUTE9 and reference_1. I have also checked with the DFF validation that the values is valid/passes DFF validation. hen I review the Journal Lines created by the transfer, the value in REFERENCE_! is successfully populated however the value in ATTRIBUTE9 is not.