How to send job notifications with dbms_scheduler via ssl encrypted smtp

We have Oracle Enterprise 19 Databases installed on Linux and using job notification via smtp with **Oracle dbms_scheduler** for quite a long time. Defining jobs like this and having all the needed settings like SMTP server, ports etc defined in dbms_scheduler attributes:

dbms_scheduler.add_job_email_notification(
  job_name   =>  'J1',
  recipients =>  'jobowner@example.com',
  events     =>  'job_all_events');

That worked fine. Now for obvious reasons our mail environment got encrypted and we need to use SSL to communicate with the SMTP server. A certificate is required and placed into a wallet. We did that using orapki and put the wallet in the filesystem location documented by Oracle $ORACLE_HOME/scheduler/wallet/

orapki wallet create -wallet /orasoft/oracle/product/19.0.0/world/scheduler/wallet/5 -pwd password -auto_login
orapki wallet add -wallet /orasoft/oracle/product/19.0.0/world/scheduler/wallet/5 -trusted_cert -cert ~/MailRootCA.cer

Inside the DB we changed dbms_scheduler settings accordingly:

DBMS_SCHEDULER.SET_SCHEDULER_ATTRIBUTE (
attribute => 'EMAIL_SERVER_ENCRYPTION',
value => 'STARTTLS');  --thats what our mailserver expects

Added the correct ports to host ace's and also a wallet ace:

DBMS_NETWORK_ACL_ADMIN.append_WALLET_ACE(
  wallet_path => 'file:/orasoft/oracle/product/19.0.0/world/scheduler/wallet/5/',
  ace     => xs$ace_type(
           privilege_list => xs$name_list('use_client_certificates', 'use_passwords'),
           principal_name => 'SYS',
           principal_type => xs_acl.ptype_db
          )

But somehow it is not working anymore. A trace file is generated each time a mail should be sent with ORA-29106: Cannot import PKCS #12 wallet. Has anyone else encountered this issue? And how to get around it? Thanks.