Hi Everyone, our PKI infrastructure is configured in a two-tier model with an offline standalone root, and subordinate enterprise ca. In our case, we began noticing this issue after our root CRL next update date passed, and we had not updated our CRL. Because our root is offline, there is a manual process to publish it, and the CRLdp is a different location than default. After publishing the updated CRL, it did not work immediately.
Hope this helps someone.