Please follow the below template, it will help us to help you!
Expected Behaviour:
pi-hole shows client hostnames
Actual Behaviour:
pi-hole show clients IPs
Debug Token: wecdmqo9v5
I use the pihole as a DHCP server and all the clients are named and have an IP at the "Static DHCP leases configuration".
Clients hostname was showing and suddenly I just can see the IP.
I have seen this behavior occasionally. In most cases, a browser refresh clears it. You might also try clearing the browser cache and then reloading the web admin page.
Not directly related to your problem, but a common question:
If you don't like the client hostnames that are shown (these are the names Pi-Hole gets during the DHCP handshake), you can enter the clients in your /etc/hosts file on the Pi and put a client name there. This is helpful if the client name that Pi-Hole has is not descriptive.
An example might be a printer - the printer tells Pi-Hole that is device "BrotherHL-5370W-wireless", but you want it to show as "office-printer".
Edit the /etc/hosts file (sudo nano etc/hosts) and add a new line with the IP for that device and the name you want: