Not a tech guy, sp I dont have a good answer but I have noticed that some posts dont load but I can see the replies. I was suspicious that the originals were on mastodon.

Pretty much every original post that nostr:npub1gkytkc0854fu5xp70mtw6096zln2njwxp3986th8qdc4l3nckkaq6ulp6z replies to that I see seems to never load. Just assumed that was why.