It seems to be a similar issue to this: https://lemmy.dbzer0.com/post/106?scrollToComments=true
I see the docs say I need to search for every comment…??? https://join-lemmy.org/docs/administration/federation_getting_started.html
But that doesn’t appear to be how it works on other posts.
Join the matrix channels. There’s a lot of other admins there who might be able to help,