I had the same issue. I was testing the feature and sent a link to my private e-mail. I received the e-mail and link, but when I 'Asked for new passcode' - I never received it.
I'm not aware of any widespread issue. Did you check the spam folder just in case?
If other emails (notifications etc.) are going out normally from the server please report this to M-Files Support so we can get the issue properly recorded and investigated.
My M-Files Notification settings was set for direct send with O365, so when you do that emails only work for internal domain users.
I re-configured my SMTP setting with smtp.office365.com and port 587 with SSL/TLs and a licensed O365 account with Authentication. Now it was able to send M-Files Notifications to external users...
