JIRA Sending JSON Payload to Azure Function but JSON Body Is Empty

Question

I have a webhook set up in JIRA to send newly created issues to an azure function app. When I send the JSON payload from that to request bin, the JSON appears as expected. When I send the JSON directly from JIRA to my Azure Function app the body is empty and the headers that it sends to the function app are different (see below):

Headers: { "was-default-hostname": "*URL*", "client-ip": "xx.x.xx.xx:xxxxx", "x-forwarded-proto": "https", "x-appservice-proto": "https", "max-forwards": "9", "x-original-url": "/api/function_name?code=*function_app_code*", "x-b3-traceid": "32f1090c7aa9e5c2b59bcbc6d2a82ac2", "x-b3-sampled": "0", "user-agent": "Atlassian Webhook HTTP Client", "x-atlassian-webhook-identifier": "581306059997554925", "host": "*URL*", "x-forwarded-tlsversion": "1.3", "x-waws-unencoded-url": "/api/*function_name*?code=*function_code*", "x-arr-ssl": "2048|256|CN=Microsoft Azure RSA TLS Issuing CA 08, O=Microsoft Corporation, C=US|CN=*.azurewebsites.net, O=Microsoft Corporation, L=Redmond, S=WA, C=US", "accept-encoding": "gzip,deflate", "x-arr-log-id": "86cb8dbb-a1b3-4e6e-bae7-2730e9d203a8", "disguised-host": "*URL*", "accept": "*/*", "x-atlassian-webhook-flow": "Primary", "x-forwarded-for": "104.192.140.244:48584", "x-site-deployment-id": "*function_name*", "connection": "keep-alive", "x-b3-spanid": "03662b7d4bb04e7d", "content-length": "0" }

What I expect to receive is the below taken from request bin:

host
enxt6nki1541.x.pipedream.net
x-amzn-trace-id
Root=1-66f52d55-538712986d5af11320ac7fb6
content-length
37486
x-atlassian-webhook-identifier
3274939199253096013
x-atlassian-webhook-flow
Primary
accept
*/*
x-b3-traceid
117d430e6304edbe25a08e21c62c8c73
x-b3-spanid
bd3641efa4233656
x-b3-sampled
0
content-type
application/json; charset=UTF-8
user-agent
Atlassian Webhook HTTP Client
accept-encoding
gzip,deflate

Does anybody know what could be stopping azure from recieving the JSON when request bin recieves it no problem?

As an additional note, I sent a payload via postman to the azure function and it sends perfectly as expected with the JSON body, correct headers etc.