Load balancer times out

Hey there, I've set up some servers on AWS behind an ALB and now I want to use cloudflare's loadbalancer for global routing

However when I call the cf loadbalancer url (https://agent.unkey.cloud/v1/liveness), it just times out
The server on aws is running though: https://agent-4c190uve.fctl.app/v1/liveness

How can I debug this further?