Same here for me. Comments aren't showing for some articles. I get email notifications for new comments on older articles and only a few of them showed the comments.
Twice now I've gone to articles from notifications and seen no comments, and sometimes while under the 10 day limit I'm having the same problem. When this problem manifests itself, I'm not seeing my profile icon or notification numbers in the top.
Reloading the page has not fixed it. The notification and which comments were new is also lost.
It appears to be happening especially on articles at the 9-11 day window. Actually, I think that's the only ones I've hit so far with issues.
https://seekingalpha.com/article/4231237-will-microns-buyback-cyclicality-problem does not have any comments showing when I click it.