Troubleshooting a routing exchange with a 3rd party has caused us to discover a difference in function between 1.1.8 and 1.2.3.
Two VyOS routers, exchanging OSPF routes through a GRE tunnel will mark received route as "invalid" and never insert it into the kernel routing table. This appears because it sees the far end of the GRE tunnel IP address as being non-reachable, despite it being ICMP reachable, and a STATIC route working correctly. This occurs when one Vyos router is in Point to Multipoint OSPF mode, and one end is in Point to Point mode.
This configuration worked on 1.1.8, and still is in production for us.