MAC address filtering is applied to the port of a Ubiquiti switch. You need to enter every MAC address on that port. It is not applied to all ports. It is not available on ports of most Ubiquiti gateways and not all Ubiquiti switches have this option. Since you are entering all the MAC addresses on one port of the Ubiquiti switch you need to connect another switch to that port you just configured.

!!! There is one problem with this feature that is not listed in the documentation, you can only filter 20 MAC addresses per port !!! No matter what Ubiquiti switch you purchase this is the limitation.

https://help.ui.com/hc/en-us/articles/18565355579799-MAC-Address-Restricting

The only way to filter more more than 20 MAC addresses is to use the RADIUS server. Follow this link for the instructions on how to do it. https://help.ui.com/hc/en-us/articles/115004589707-MAC-Based-VLAN-Assignment-Using-802-1x-in-UniFi-Network