Yeah this is an issue I used to face as well. And it is not limited to your comments. Comments from other people were also collapsed and wouldn't load when expanded. I used to think the comment must have been deleted or removed but then those comments used to load up in the lemmy-ui on my computer and on other lemmy clients like voyager, jerboa, etc.
https://lemmy.one/post/3173200.
Edit : reading your post more carefully, maybe we have different issues