PSA: if a remote community hasn't been fetched by your instance yet, you need to search for it
I've seen this mentioned a few times already: people wondering why certain communities don't show up in their instance. You need to first search for that community via the magnifying glass icon and type in "!communityname@instance.domain"
Notice the exclamation mark at the beginning. Might take a few seconds. This will teach your instance about the remote community.
Any idea if there is a delay in community searching? Someone mentioned a newly created community (1 hour ago) on sh.itjust.works and I searched on lemmy.world for it and nothing but I can visit it directly.
I have in fact noticed a 1-2 minute delay when searching for a completely fresh comunity from lemm.ee. Initially the search turns up 0 results, but trying again in a minute will find the community.