networkd backend ConfigureWithoutCarrier=yes breaks static address and routes

[msaxl]

When upgrading from 18.04 to 20.04 rc the bridge network did not work anymore. After booting a manual neplan apply fixed it for the current boot. But upon rebooting the problem arouse again.

the configuration consists of a bride, a port to connect to the bridge and both static ipv6 and ipv4 addresses. The gateway is set as route to 0.0.0.0/0

The new netplan adds ConfigureWithoutCarrier to the bridge configuration. This seems to not work in that case
This is the output:
Apr 20 18:30:04 srvau02 systemd[1]: Started Network Service.
Apr 20 18:30:04 srvau02 systemd-networkd[507]: br0: IPv6 successfully enabled
Apr 20 18:30:04 srvau02 systemd-networkd[507]: br0: Link UP
Apr 20 18:30:04 srvau02 systemd-networkd[507]: br0: Gained carrier
Apr 20 18:30:04 srvau02 systemd-networkd[507]: br0: Lost carrier
Apr 20 18:30:05 srvau02 systemd-networkd[507]: eno1: Link UP
Apr 20 18:30:05 srvau02 systemd-networkd[507]: br0: Could not set route: Nexthop has invalid gateway. Network is unreachable
Apr 20 18:30:05 srvau02 systemd-networkd[507]: br0: Failed
Apr 20 18:30:07 srvau02 systemd-networkd[507]: eno1: Gained carrier
Apr 20 18:30:07 srvau02 systemd-networkd[507]: br0: Gained carrier