I just joined the NZ lemmy here, because Lemmy.world was slow. This instance is much faster for me, but when searching for communities, many that I was subscribed to with my lemmyworld account didn't show in the search results.

I fixed this by manually finding it in the address bar, like this:

https://lemmy.nz/c/linux@lemmy.world

And this will work for all communities, just replacing the appropriate parts:

https://lemmy.nz/c/[communityname]@[instancename]

Then you can subscribe and it will show in your 'Subscribed to communities' on the main page. (sometimes I have to refresh for all to show up).

This might be a known issue at the moment, but I've only been on Lemmy for like 3 days so idk