The user certificates from the REDDOXX Root CA are no longer valid and are classified as "Unknown CA".
A yellow exclamation point is shown next to these certificates in the list of user certificates.
Perhaps the Root CA was first exported and then imported to the Public Certificates storage.
The root certificate (found under Certificate Authorities) has an invaild status.
1. Delete the root certificate again.
2. Simply change the status to valid (trustworthy)