Function executions via custom domain from UI hangs, execution from client SDK works normal

Aplogies if this was asked already. I'm self-hosting 1.9 on a self-hosted instance of Dokploy. I've made the necessary adjustments to the original compose file (like removing traefik service in favour of Dokploy's already deployed traefik) and have deployed it with minimal issues so far. The main domain worked fine.

Now I'm running into a weird issue where triggering an execution using the generated custom domain for the function would cause it to hang for a bit - or sometimes indefinitely before the main Appwrite instance returns a 500 error page. No mention of this error anywhere in the logs - appwrite, appwrite-worker-functions and openruntimes-executor are silent.

I've setup a self-hosted ACME-DNS server to auto-generate SSL certificates for wildcard domains and I've verified the DNS settings to be working.

Executing the function via Client SDK works fine, even works with postman by copying over the cookie and project id headers just to double check. I'm heavily leaning on this being some routing issue within Appwrite and I'm probably missing (or misconfgured) a config or two.

Alternatively I can ditch the preview URLs but I want to know the cleanest way. In the docs it says removing _APP_DOMAIN_FUNCTIONS disables the preview URLs feature but I get an error saying missing value when I go to the functions page.