Load balancer acting crazy

Hi there! i’m having a very weird issue with the load balancer. Here’s the scenario:

I have setup 1 pool with 2 origins, one pointing a shopify site and the other a vercel site.

Now if i play around with the weight and set 1 to shopify and 0 vercel, it works no problem when i hit the load balancer, it always shows me the shopify site alone. If i do the other and set 0 to shopify and weight 1 to vercel it also works perfectly, it shows me the vercel site every time.

Now… if i set any other weight distribution like 50/50 or 95/5 things go wild. I get 404 from Vercel saying the deployment was not found, i get 525 handshake errors from cloudflare, and even sometimes get 404 from shopify saying the domain does not exist in the store.

May this be related to the host header?

Here’s how that looks like: Screen Shot 2021-10-06 at 10.31.41 AM

Please let me know, i don’t know what else to do