Alstom/Converteam Series 21

Has anyone who has worked with Alstom Series 21 experienced this one?
While on DP the operator changed the draft to accommodate for a change in draft due to loading. The system “mysteriously” put the draft to 0.0 m. The system will not let you enter anything lower then 2.6 m.

I have worked extensively with that system.
What did the operator try to change the draft to?
It makes sense that there is a minimum. At zero draft you wouldn’t have any props in the water, so you wouldnt be able to DP anyways!
I wonder if when the system is initially configured if the minimum is a function of that vessels prop size…?

The operator changed the draft from 3.5 m to 4.6 m due to loading of weighted mud. But, there was not indication on the print out that the change was made. Only the 0.0 m draft change. As far as the initial set up, I do not know what it was.

It sounds like a malfunction in the program.
Either that or operator error.