AWS LB sandwich does not come up healthy in some cases

[rohan_savant]

we have an AWS ingress gateway auto scale group deployed. We have all routing setup between accounts using tgw.

However, and this is random, some of our External load balancers with targets as gateways do not come up healthy. this is completely random but once comes up as unhealthy it never turns healthy for that particular lb. 

i am able to curl from the gateway to the internal LB and the internal LB is healthy and can be hit directly and shows the webpage.

Setup:

External lb:

Listen port 443

Target port: 9500 (doesnt come up healthy but autoprov and provisioned the rules)

Internal LB:

Listen port 443

Target port 443

TAG-: x-chkp-forwarding-  https-9500-443

any idea what could be happening here? we are not doing https inspection, just passing from https traffic.

thanks

Rohan