Problem Posting Vendor Payment that Applies Multiple Vendor Invoices and Credit Memos

After posting the Vendor payment in NAV2015, the credit memos are left open and not applied in full.
EG: INV's for -400 and -100, CM's for 75 and 60. Payment therefore for 365.
After dealing with two invoices posting routine applies only 15 for CM of 75 and nothing for CM of 60.

Does anyone know about this problem and or have a fix for it?

I believe problem may relate to GetAppliedAmountFromBuffers function in CU 12.