I checked your domain.
We got an error from our cert authority:
Failed to create Order: 429 urn:ietf:params:acme:error:rateLimited: Error creating new order :: too many certificates (5) already issued for this exact set of domains in the last 168 hours
In this case, the easiest way is to create a new subdomain for your sGTM.
I think this is connected to your open ticket in our help desk.