WBS_element – Message 5W225 : Assignment could not be maintained

[Magda10]

Dear all

When we trying to assing employee to a WBS-element in CJ20N I am getting the message: 5w225 - Assignment could not be maintained. 

We just opgraded to S/4HANA 2023 FPS1, and after that we getting this message. Normally we are assing the employees by person and then employee number. This is the faster way to do so. We know that there are others way to do the samme but they are not so friendly.

Does anybody has seen this message before?

Thanks in advance