OSPF stuck in Exstart

Hello,

I am facing an issue with enabling OSPF between a Cisco Router and F5 LTM. The OSPF adjacency process is getting stuck at exstart phase.

This is how my toplogy looks like:

Cisco Router<-------Cisco L2 Switch------->F5 LTM

LTM-01[2]>show ip os neighbor

OSPF process 26:
Neighbor ID     Pri   State           Dead Time   Address         Interface
10.10.26.9        1   ExStart/Backup  00:00:37    172.16.207.2    /Inbound
10.10.26.10       1   ExStart/DROther 00:00:34    172.16.207.3    /Inbound
LTM-01[2]>

From debug in Cisco Router:

863027: Aug  7 11:37:12.920 PDT: OSPF-26 ADJ   Gi0/1: Send DBD to 172.16.207.254 seq 0x238E opt 0x52 flag 0x7 len 32
863028: Aug  7 11:37:12.920 PDT: OSPF-26 ADJ   Gi0/1: Retransmitting DBD to 172.16.207.254 [8]

Here I can see that the router is actively sending DBD packets to F5, but no reply back.

All the device are running interface MTU of 1500 bytes. I am not sure how to debug OSPF in F5 device.

Any help would be appreciated!