OSPF network type mismatch on a multi-access link is causing route summarization issues. Router R1 and R2 are connected via Ethernet, but R1 has:

interface GigabitEthernet0/0
 ip address 10.0.0.1 255.255.255.0
 ip ospf network point-to-point
 ip ospf 1 area 0

!

Router R2 has default OSPF network type (broadcast). R1 is configured with:
router ospf 1
 area 0 range 10.0.0.0 255.255.255.0

! R2 shows:

R2# show ip ospf neighbor
Neighbor ID     Pri   State           Dead Time   Address         Interface
10.0.0.1          0   FULL/  -        00:00:30    10.0.0.1        GigabitEthernet0/0

But R2 does not have the summary route in its routing table. What is the root cause?