Unable to verify answer from IDP

[neufeind]

When using a login against a Microsoft IDP I was unable to validate the incoming answer. Debugging showed that it tries to use our certificate from the CredentialStore, but would instead need the idp_certificate.
As a fix using instead
$certificate->loadPem($row['idp_certificate']);
worked. But of course then the lines below regarding the private-key don't make sense here anymore.

mksamlauth/Classes/Store/CredentialStore.php

Line 42 in fa155ab

$certificate->loadPem($row['certificate']);

Does the extension "as is" (used the 8.7-branch) work for others? How come they don't have problems validating the answer from the idp?