When updating rows using the CDS Current Environment Connection lookup values must be proceeded with the entity name for the reference. For example;
But what if the ID is empty? In that case an error wil occur because the reference is null.
There is a (really nasty) solution to get around this, using a formula in stead of the entity name + GUID:
And the formula is:
If anyone has a better solution, please let me know :-).