Recently, after everything had been working fine, banner notifications (from my two apps that generate notifications) are appearing in a transparent mode (see screenshot). (I'm not using Dark Mode.) It seemed to start suddenly.
What's causing the transparency?
iMac 27", macOS 10.14
I found an earlier thread about this, with more activity. Also, they suggest to kill Notification Center (via Activity Monitor), but the issue returns eventually. Might be a bug in OS 10.14.
"Notifications are Transparent and non-clickable"
Better thread: https://discussions.apple.com/thread/8594881
Try from >System Preferences>Accessibility>Display
That Accessibility setting has no effect.
Notifcation banners appear, but are transparent and dim
