Recently added OSPF to a new router in my network
Ospf appears to be only seeing the neighbor on one side of a link, but not the other
Two nodes involved, the "stub" router isn't seeing the "core", but the core is seeing the stub. Areas are correct, it's the same with or without authentication. I'm sure I'm missing something obvious, but it is eluding me at present. Done the same way many times in this network and it works fine! FW all the same bugfix 6.38.7
Appreciate any ideas why it's happening?
Thanks!

Check your firewall for any filter o nat rules that may be getting into OSPF's way.

Other things to check:
MTU
OSPF Interface type (p2p vs broadcast vs NBMA etc)
Passive interface?
Both routers have the correct OSPF network defined to include the common interface between them
If there is some 3rd party wireless bridge between the devices, make sure it's not blocking multicast
probably a couple of other things I'm not thinking of right now