I seem to encounter this often while using Sync, and have so for the past couple of years. Not sure why it's taken until now to ask about it. The issue is always as shown here. I'll open a post, even one that I've interacted with and have received replies, but despite my efforts I can't get it to actually display the comments. This seems to happen completely at random, and perhaps as often as 1 in 8 posts. Comments work completely fine elsewhere.

Clicking "View post" via the prompt at the bottom makes no difference.

Any ideas?