Hi Ravish,
Please check the Work Center Capacity Category. It must be 002 - Labour.
If it is, for example, 001 - Machines, Logically, you will not need to give any Employee names.
Please also check the control key in the Work Center which you are using.
You were mentioning that you are facing this issue for the last few days.
Please let me know if this is the same across all Order Types and Work Centers.
Best Regards
Veera