APP-FND-00698: Flexfield segment combination not found

When users open up a manual invoice transaction and click the line items the following error is thrown:

APP-FND-00698: Flexfield segment combination not found.

Inform your system administrator that the combination identified by the unique ID number 21590 could not be found in the combinations table for the flexfield structure identified by Application = INV, Flexfield Code = MSTK and Structure Number 101

I found that this error is occurring when it appears there is no item assigned to the line (by viewing it from the UI), but when you query the ra_customer_trx_lines you see an item is actually assigned.

The issue started occurring after RPC5 patches were applied. The issue cannot be replicated in our dev environments without RPC5 patches.