I am having this same issue. The DHCP server is running out of addresses. There are a bunch of addresses with the bogus MAC address up top in the title. These bogus MAC addresses simply translate to the IP addresses they are taking as well, so they are not MAC addresses. Therefore you cannot search by switch to locate the device. Tried Wireshark. Started a session, then deleted the bogus addresses from DHCP server. Waited a bit, then reconciled DHCP server. Bogus addresses all came back. Stopped Wireshark session. Looked at all the DHCP data, and none of the bogus ip addresses even show in Wireshark.
This is bizarre. It is like the addresses are not really gone, but my DHCP lease table is full.