I have an unread DM and when I click on it I get a blank white screen. Happens in safari and chrome.
I see this when I click on a notification of an answer or reply after having been away; goes to a blank white screen on Chrome (mac & win 10) and Firefox (win 10). Only way to get back to refresh, going to the course home page, find the notification again (not easy because it is no longer unread), and follow again. Then it will bring up the post+answer screen.
A related case is described here: https://campuswire.canny.io/bug-reports/p/after-clicking-on-image-in-answer-cant-return-to-post
The hangup is somewhere between marking the notification as read and showing the screen. (It would be a little less annoying if the notification was not marked as read until the screen was shown.)
Apologies for the hassle @Noah White: looking into it now