I had the same problem. I was able to get it working by installing the certs into my meraki generated profiles then on a mac running:
profiles list
find the profileid
profiles show profileid
Find the certificate required and grab the UUID
_computerlevel[1] payload[9] name = CertificateName
_computerlevel[1] payload[9] description = Credential
_computerlevel[1] payload[9] type = com.apple.security.pkcs1
_computerlevel[1] payload[9] organization = Meraki, Inc.
_computerlevel[1] payload[9] identifier = com.meraki.sm.credential
_computerlevel[1] payload[9] uuid = c59e77b0-3ea7-0137-75cd-6d6572616b69
Remove the certificates from the .mobileconfig and paste the UUID into the payloadcertificateid
<key>PayloadCertificateUUID</key>
<string>c59e77b0-3ea7-0137-75cd-6d6572616b69</string>