Manager can't add participant in performance document

Hi,

as a manager role, in production environment, when I try to add participants on performance document of my direct report (the task of the document is on self-evaluation or managerial evaluation)(the managerial evaluation is not completed) I see in the drop down menu the list of the employees, but when I select one of them I can't see the selection.

I added screenshots of the issue in the word file.

Thanks,
Imma.