Alert acknowledge URL's not working. Just shows IP:Port, no suffix

I'm not getting full URL's in alerts. An example output is

Customer Router: MyCustomer (MikroTik) - - is Critical
Mute Alert:

This is not useful as it links to the main portal page. I'd expect something like to show up

Any ideas? This is a new alert that I created so maybe I need to add something else. I.e. do I first need to have a trigger action that sends to NetPerf or just a dummy rule in order for it to create the alert, and then escalate it a minute later for it to appear in the slack message?

This is the payload of the HTTPS POST

payload={"attachments":[{"text": "HU: ${N=SwisEntity;M=DisplayName} (${N=SwisEntity;M=Vendor;F=OriginalValue}) - ${N=SwisEntity;M=IP_Address} - is ${N=SwisEntity;M=Status;F=Status} \nMute Alert: ${AcknowledgeURL}","fields":[],"color": "#ffa73d"}]}

The only important bit there is the ${AcknowledgeURL} i'm assuming this is the correct syntax