Why is my printer's IP not shown in the client overview in the omada webinterface?

I had to use a network-IP-scanner to identify the IP-address of the printer since I forgot it.

The IP is manually assigned directly to the printer in the printer itself, not via Omada.

The Omada system in itself seems to have an issue with fixed-IP-devices in general. 

In the above image (devices ordered by IP) you can see Omada fails to show the printer with IP ending in .8.40