Fixed Planned Orders cannot be changed anymore

Hello Experts,

we have seperated the fixed planned orders from the planned orders by creating a new category group which contains

only EE fixed, leaving EE unfixed in Category Group FP1.

We then assigned the fixed orders to a new KF. Now we have the issue that we cannot change the value of the fixed orders anymore. The new KF is automatically set as "no entry allowed". How can I change this and why is it automatically set to "output only" Keyfigure?

Thanks a lot for any ideas.

BR Julia