Hello Roger,
please generate a debug log as described below and send it to us at support@boxcrxptor.com, referring to the post here:
https://www.boxcryptor.com/en/help/faq-and-troubleshooting/windows/#how-to-create-a-debug-log
In the meantime you can use the Windows tools as a workaround to disable the notifications (but it will disable ALL Boxcryptor notifications, remember this):
https://www.laptopmag.com/articles/disable-app-notifications-windows-10
Best regards,
Yasmin