Tested with mails from bsi.bund.de, subject e. g. from today
[Buerger-Cert-Warnmeldung] TW-T20-0127 - Mozilla Firefox für Android: Schwachstelle ermöglicht Offenlegung von Informationen
or with emails from a colleague sent with Tobit David
or with all mails from email@example.com, subject "Microsoft Security Update Releases" e. g. 2020-06-12.
This bug exists already for a very long time (I thought it was a fault on the sender's side since yesterday when I tested :-).
We sent test emails to Office 365 (Enterprise), Outlook.com, gmail and gmx.de in CC - the same email without issues, URLs clickable, if viewed in a web browser and in Outlook 365 as soon as we disable the GpgOL Add-In. Re-Activating breaks the URLs again.