CO06 "Please select a line that can be changed" - Unable to see blue lines

Hi team,

I have a problem related to CO06, error message AG755: "Please select a line that can be changed".

When I enter to a specific material/plant in CO06, I can see that all the lines are confirmed and black. Any of the sales orders confirmed appear in blue, meaning able to change the confirmation.

I have been reading all similar issues and I can say that the problem is NOT coming from:

- Confirmation at storage location level (1773701 Note)

- Product Selection Item (1773701 Note)

- Running ATP_VBBE_CONSISTENCY. Programchecks and everything OK, no differences.

Am I missing something else?

What could be the cause of this error?

Thank you!

Eva