DRS Functionality with ROBO Enterprise License is not full DRS functionality.

There are some limitations you should be aware of before you initiate maintenance mode on a ROBO Enterprise cluster. On a ROBO Enterprise cluster, DRS is disabled by default. If you have migrated from a DRS supported license to a ROBO Enterprise license, you may have VMs with affinity or anti-affinity rules present in the system. You must disable or delete VMs with affinity or anti-affinity rules or the ROBO Enterprise maintenance mode operation is disabled. ROBO Enterprise maintenance mode operation is disabled if DRS is not set to fully automated mode. DRS automation level must be set to fully automated mode in order to evacuate VMs automatically through the host maintenance workflow. If a VM overrides DRS fully automated mode, you must evacuate the VM manually.