Investigating this issue, it looks like there are several issues with the rename code:
1) "DEBUG:Skipping non-physical interface: enp6s0" -> The rename code seems to ignore interfaces which are matched by name/mac/driver rules (glob). It seems to just consider direct matches between netplan ID & interface name.
2) The logic for renaming interfaces via "udevadm test-builtin net_setup_link /sys/class/net/IFACE" && "udevadm settle" seems to do nothing, i.e. not actually renaming the interface.
Investigating this issue, it looks like there are several issues with the rename code:
1) "DEBUG:Skipping non-physical interface: enp6s0" -> The rename code seems to ignore interfaces which are matched by name/mac/driver rules (glob). It seems to just consider direct matches between netplan ID & interface name.
2) The logic for renaming interfaces via "udevadm test-builtin net_setup_link /sys/class/ net/IFACE" && "udevadm settle" seems to do nothing, i.e. not actually renaming the interface.