Thank you Nagarajan K!
When you tried and were sure that it did work, I knew something was off on my side because it still gave me issues.
I've been running tests and what I found was that the issue I described before occurred when entering the sales order number manually. If I go and select the sales order from the CFL, then OriginAbs is always populated. It's kind of an inconsistency in BOne I guess...
But thanks again for helping me dig dipper into this issue!