Using Certificates in Azure API Management

Hello

I am using a digital certificate for the Azure Api Manaement domain.

I added the intermediate certificate to the certificates section, according to the section "Custom Domain with Custom CA for Cloud Gateway".

When I validate my certificate xxx.xxxxxxxx.xx using:
https://www.digicert.com/kb/ssl-certificate-installation.htm

I am getting the following error:

"The server is not sending the required intermediate certificate."

when I check in Application Insights I can see this:

"xxx.xxxxxxxx.xx Unable to match incoming request to an operation. OperationNotFound at configuration."

Any idea how I can get this to work.

Thanks