Fix confirmed! I can now see comments while logged in, as well as a more explanatory message "(You have insufficient privileges to post comments.)"
Thanks for addressing that bug and providing the additional context about new user capabilities.
I wonder if the threshold is affecting me as well; I created an account specifically to ask questions about and provide feedback on an article[1], and while I was able to start private conversations with the author, I am unable to even see the article comments while logged in.
[1]...