IPSEC Transport Mode brings down GRE Tunnel

[xtropx]

Hello.
I have a GRE tunnel between two sites set up and working fine. Using OSPFd to transmit routes between them. I set up IPSEC in transport mode using the public IP addresses between sites and instantly I can see the GRE tunnel go down. I check status > gateways and they are offline. Nothing in IPSEC log that would indicate a problem with the IPSEC tunnel itself. status > ipsec does have the yellow X "error" but appears to set up properly.

I am just wondering if there is a better way from a design perspective to do this, whether it be with pfsense or in some other fashion. I was looking into OpenVPN but I am unsure whether I can get OSPFd working over that tunnel either. If all else fails I will just do some redesign of IP addressing and use a summary route over IPSEC in tunnel mode, or with OpenVPN, but I would like to continue to use OSPFd if possible. Thoughts?

[cmb]

That means your IPsec isn't setup correctly. That scenario works where transport mode IPsec is properly configured. It also works with OpenVPN.

[xtropx]

Hi I am back again. I've been using IPSEC in tunnel mode for a while but I am giving transport another go.
I have tried again and I cannot get IPSEC transport mode to come up.
I have disabled IPSEC ESP and am just using AH for the time being.
I have allowed both protocols on the WAN interface (ESP & HA) from the public IP address of each side to "any" (as well as ICMP from either sides)
Prefer old IPSEC SAs is OFF

I have:
IP: IPv4
INTERFACE: WAN
REMOTE GATEWAY: PUBLIC IP OF OTHER SIDE
AUTHENTICATION PROTOCOL: Mutual PSK
NEGOTIATION: Agressive
MY IDENTIFIER: My IP Address
PEER IDENTIFIER: Peer IP Address
PRESHARED KEY: <psk>(COPY & PASTED, THEY ARE THE SAME)
POLICY GENERATION: Default
PROPOSAL CHECKING: Default
ENCRYPTION ALGORITHM: 3DES
HASH ALGORITHM: SHA384
DH KEY GROUP: 2(1024 bit)
LIFETIME: 28800
NAT TRAVERSAL: DISABLE
DEAD PEER: UNCHECKED

And for Phase 2:

MODE: TRANSPORT
PROTOCOL: AH
HASH ALGORITHMS: MD5
PFS KEY GROUP: OFF
LIFETIME: 86400
AUTOMATICALLY PING HOST: BLANK

I know in IPSEC it is CRITICAL to make sure sides match, so I have ensured. I've deleted the SPD on both sides and restart racoon and still comes up with "error" under Status > IPSEC. No obvious errors in the logs (Ive googled just about everything in there)
GRE is up and running, with OSPF over it. I can ping/access my remote subnets, but it breaks when I turn on IPSEC. I'd be really grateful for any ideas!</psk>