Given the settings in Settings / Directory Services:
- OpenPGP keyserver set (e.g. hkp://keyserver.ubuntu.com)
- Query certificiate directories of providers for all user IDs checked
Via context menu: Update Certificates: the certificate is successfully fetched via WKD.
Via main menu: Tools / Refresh OpenPGP certificates: only the openpgp keyserver is checked, not the WKD.