Puzzling OSPF Pathing

Hi everyone. I've got a head-scratcher, and wondering if /r/networking can help me understand the behavior OSPF is exhibiting.

The topology is here: https://imgur.com/a/MPRg3DO

The hardware is mixed variety, Brocade, Fortigate and some Ubiquiti.

I can't figure out why OSPF is routing traffic from Host A destined for R5 the way it does (green arrows), while a lower cost option exists directly from R2 to R4.

Egress traffic from R5 back to Host A does utilize the R4-R2 path, just not inbound. I think it might be due to some inter-area nuances, but just can't seem to put a finger on it.

Thanks for any insights!

edit: some more info. Destination on R5 is 192.168.168.128/26.

'show ip route 192.168.168.128 detail' on R2:
Interface 1/3 is the interconnect between R1 & R2.

telnet@rtr-02>show ip route 192.168.168.128 detail Type Codes - B:BGP D:Connected I:ISIS O:OSPF R:RIP S:Static; Cost - Dist/Metric BGP Codes - i:iBGP e:eBGP ISIS Codes - L1:Level-1 L2:Level-2 OSPF Codes - i:Inter Area 1:External Type 1 2:External Type 2 s:Sham Link STATIC Codes - d:DHCPv6 Destination Gateway Port Cost Type Uptime src-vrf 1 192.168.168.128/26 192.168.161.28 eth 1/3 110/246 Oi 9h49m - Nexthop Entry ID:65536, Paths: 1, Ref_Count:100836/100837 D:Dynamic P:Permanent F:Forward U:Us C:Connected Network E: ESI VLAN W:Wait ARP I:ICMP Deny K:Drop R:Fragment S:Snap Encap N:CamInvalid Module S1: IP Address Next Hop MAC Type Port Vlan Pri 192.168.168.128/26 192.168.161.28 0012.f290.b102 PF 1/3 1 0 OutgoingIf ArpIndex PPCR_ID CamLevel Parent DontAge Index Is_trunk eth 1/3 3 1:1 1 0 54539 0 U_flags Entry_flags Age Cam:Index HW_Path_count 0000e000 0 0x00011ca8 (L3, left) 1 CAM Entry Flag: 00000001H PPCR : 1:1 CIDX: 0x00011ca8 (L3, left) (IP_NETWORK: 0xfc357) pram_index_programmed: ppcr[0] 0x0007fedb 

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show ip ospf database on R2 (snipped to relevant network):

192.168.66.1 is ID for R4.

192.168.162.9 is ID for R3.

180 0.0.0.0 Summ 192.168.168.128 192.168.162.9 80000014 1573 0xde57 Done 181 0.0.0.0 Summ 192.168.168.128 192.168.66.1 80000014 1414 0xe2ae Done 

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