Win 10: Signed/Encrypted EMail: DGN S/Mime Certificate prompts Error

Email Cert provided by german provider DGNCert is successfully imported in local Win 10 machine , also all root certificates by DGN. Cert is imported in EM-Client, also all root certificates, show up in Certs as my/others accordingly. Signature Badge Icon is active when selecting proper email account for sending, when sending Error message states there is no valid cert fot the given email-sender, as the locking-list could not be checked. Bad translation on my side, i guess emclient is checking the validity of email and root certs at the cert authority against deleted or expired certs and could not get a proper result.
Outlook is sending the signed message flawlessly, but emclient displays a Signature-Problem with the message, stating the same error message, could not verify locking-list. Is this a em-client error or should i contact DGN?
the node for locking-lists is stated as

Actually Ih do have the same problem (also using a DGN certificate)
Did you find a solution yet?