Why does it say there are comments but not display any?

When that happens to me it's because I've blocked whoever made the comment. I've never experienced 13 people I blocked all commenting on the same post though so I'm not sure if that's what's happening here... Do you block a lot of people?

No, like I said to the other reply. I certainly haven't blocked 13 people individually, and I haven't blocked lemmy.world
If you block someone, the replies to their comemnts get hidden as well.

The guy is on vacation, he'll give you his comments on Monday.

If you haven't blocked anyone, any communities or instances then check you have both English and Undefined selected in language settings (along with other languages you want to see posts/comments in).

I have confirmed I do have those both enabled
I can't find language settings under either General or Appearance
- Try logging in via browser and checking Account or Profile.

Voyager often has strange sync issues. I find that attempting to reload the post (just pull down while viewing comments) will often work to load the comments. If that doesn't work, I find that reloading the entire feed will generally fix the issue

I wonder if this is related to sync having the same issue. I frequently find threads with 5-10 comments but nothing shows up. I don't have anybody blocked whatsoever and the issue happens on posts from various instances, even my own. Maybe this could be a bug that affects both apps. When I load these threads in browser it looks fine.

This was the more plausible theory the last time I looked into it - some kind of sync lag.

The ones making the comment are on your block list, either personally, or by instance.

All 13 of them? I don't block lemmy.world, and it's unlikely there would be that many from hexbear, and I've only individually blocked a couple of people.
- If the top level comment is by a blocked user, you won't see the rest of the comment tree either

I thought lemm.ee might be lagging behind as it shows fine in my voyager, but the comments display just fine on lemm.ee. Have you tried refreshing? Sometimes I have this happen and just a refresh will load them.