I've seen a similar situation where Pi-hole has the wrong hostname for an IP because it previously saw the hostname with that IP, even though the hostname has now changed. Flushing the network table and restarting the DNS resolver didn't fix it. I posted an example in a different thread.
In my case I think it was a PTR request against the IP of the wrongly named host which updated the name in Pi-hole and made it display correctly from that point onwards.
Your situation looks slightly different because it relates to your static entry for Dennis-laptop seemingly not being picked up. Nevertheless it would be interesting if you could do a PTR request against the IP and see if that changes anything. Perhaps some similar naming update mechanism is at play. You can use the dig or nslookup command to do this, from any client which is using Pi-hole for its DNS.
(Edit : assuming that your static entry is still present, if not then please try adding it back again)
dig -x 192.168.2.245
nslookup 192.168.2.245
Does that return Dennis-laptop or LAPTOP-V1HR47PC? And if it returns the correct name, is it now showing as the correct name in the Query Log too?