This forumpost might explain your issue. https://forum.mendix.com/link/questions/96621
I'm not sure if Mendix already fixed the issue.
The data may not be transferred or processed correctly when you retrieve it from the object. Check that the object contains all the required associations and that they are filled out correctly. Review your workflow logic and ensure that data is processed correctly at each stage of execution. If necessary, debug your code or workflow to identify possible problems or errors.