Before I describe the issue I'm observing, I want to let you know that I have the Catalina beta installed on my machine. So, perhaps, if someone with Mojave or an earlier version of macOS is also experiencing this issue they can confirm. Otherwise, this may just be a problem associated with the beta OS. Disclaimer aside, here is the issue.
I am experiencing two main problems that I've been able to observe. First, the the small triangle menu button on the right side of a courses card (for started courses) does not do anything. It's clear that it's trying to do something because the entire Courses window goes unresponsive after clicking it.
Second, the courses window will go blank (white) sometimes, but I am not sure what is the trigger cause or how frequently it occurs. Once it goes blank, I can refresh it only by closing the tab and opening it again.
I'll supplement this if I have any more useful observations about this issue.