Sage 2013 (5.0) MAS 100 Premium with SQL PU4

Summary: Setting FreightAmt on Pre-Write in a Credit Memo generated by RMA results in Credit Memo amounts turning into positive amount – including NontaxableAmt, TaxableAmt, SalesTaxAmt, DiscountAmt, etc. When the *Credit Memo is being posted, it creates an out of balance journal entry.

My goal here is to have an option in RMA Receipts Entry so that when the Credit Memo is generated for a refund from RMA, the invoice would automatically include the Freight Amount that was billed in the original invoice. I’ve tried some very simple codes in the Table Pre-Write on SO_InvoiceHeader for Credit Memos, which resulted in the same behavior – amount turning into positive numbers.

retVal = oBusObj.SetValue("FreightAmt",10)

I've read through the product update release notes from the latest patches, but didn't see this behavior being mentioned. Is this a bug? Can someone reproduce the same error? Any help would be appreciated!