I have created a static ip (B8:27:EB:F9:7D:A2 - 192.168.2.22 - domoticz) for a Pi, however when I switch on this Pi it always gets assigned a pool IP (B8:27:EB:F9:7D:A2 - 192.168.2.248 - domoticz).
There's another Pi which has the same behaviour, static (E4:5F:01:04:E0:29 - 192.168.2.24 - volumio) but always gets pool IP (E4:5F:01:04:E0:29 - 192.168.2.239 - volumio).
All other Pi's and systems get the assigned static IPs.
I can delete the pool assignment, however they get back the same pool IP.
What am I doing wrong .. any tips and trics are highly appreciated since it drives me mad
I can think of two potential causes for your observation:
a) As your device already has a grip on an IP address from your network, it may hold on to that and explicitly request getting assigned that address.
b) pihole-FTL's embedded dnsmasq DHCP server is already making an effort to hand out the same IP to the same requesting MAC.
So commonly, you'd end up with the same device acquiring the same IP address any time it requests a DHCP lease through Pi-hole (it's just that IP was chosen by dnsmasq).
As dnsmasq is already aware of that MAC having acknowledged that IP address, it may treat the DHCP message as a request for renewal (even more so if a) would apply for that device at the same time).
You could try the following steps to mitigate this:
power down your client device (the one that should get the fixed IP)
delete the DHCP lease from the list of Currently active DHCP leasesvia Settings | DHCP
