Notification Center hangs—but only on external display

[wills11]

Since upgrading to Big Sur on my 2019 iMac 5k, Notification Center intermittently-but-frequently uses 100% CPU before crashing with a spinning beach ball when I try to click on a notification, and has to be quit in Activity Monitor in order to get it to work (and get it to auto-hide again)—but only on the external display. On the iMac display, it works fine.

The external display is a BenQ PD3200U connected via the stock BenQ HDMI-to-USB-C cable to a Thunderbolt 3 port on the iMac. This happens regardless of which monitor is "primary" (i.e. has the menu bar in System Preferences —> Displays —> Arrangement).

Anyone else have this odd issue or any suggestions?

Thanks in advance!

 

[atrisk]

I have seen the process crashing every few hours if opened. I only have one screen... If i force quit the process in Activity Monitor it works fine for a few more hours then happens all over again. does not see to affect anything else when it has crashed and startup instantly after a force quit.

 

[wills11]

Very strange. Mine crashes, usually (it seems) when I click on a Mail notification. Same deal—when I force quit, it immediately restarts. Wonder what it is...