Certificate Management for Microsoft CA not pulling all certificates issued

[MMGF]

I am running a Certificates discovery on an in-house MS CA root cert server. 

I used template_list of 'all' in the pattern "MicroSoft CA - Certificate Management".
It discovers about 700 certificates. The client insists that the server has issued over 1100 certs by looking at the MS Server GUI. 

What might be the issue here? How can we validate/reconcile the discrepancy?

Thanks