You CAN scan Xen servers. Lansweeper just won't tell you which virtual machines are hosted on each server. You can scan the guests as separate assets; they just won't be linked to the Xen server.
Ouch 😞 anyway to possible run a report or custom something to do it? We have over 100 xen hosts, and a few hunted other but its the xen and citrix models we need to keep track of