Bug: comments are present under blog post, but misisng in admin panel

[rexTexTau]

Steps to reproduce:

1. Create a comment under the blog post (i.e. https://personal-blog-demo.platformus.net/en/blog/post-2)
2. Ensure comment appears under it.
3. Go to admin panel, Objects -> Blog post, and click on the corresponding Comments link (i.e. https://personal-blog-demo.platformus.net/backend/objects?class.id=4&primary.id=11).
4. Ensure there are no records shown, although records do clearly exist in the database.