And the fact that you can see some leases but virsh doesn't report any
suggests that you may be using type='bridge'.
indeed, I modified the configuration to 'network' and now it works.
# virsh domifaddr --domain wec --source lease
Name MAC address Protocol Address
-------------------------------------------------------------------------------
vnet2 52:54:00:0e:ee:da ipv6 2a02:xxx:xx:7::1ba/64