Custom Fields on Limit POs not updating in ECC

All,

We are Extended Classic Scenario 7.01 

ECC - 6.04

For NON-limit POs, we have successfully added custom fields to the PO line item level in SRM and they appear in the PO created in ECC.  This, however, does not work for limit POs/items.   The values are being passed to ECC successfully, it is just they do not appear on the PO that is created.   We do not get any errors or warnings.

Thoughts?

Sandra