I am having the exact same problem. Posts display, but do not offer any place to make a comment. The only thing I see is an “edit” which you can edit the post with. I am relatively new to WordPress, and have been trying to tweak the code.
The best way, which isn’t exactly a pretty way of doing it, is to grab index.php from the classic theme and copy it over. From there, you can tweak it to get it looking right.
Hopefully, this will fix your problem.
