Yes, I can help :)
Hashtags by themselves are just passive filters for whatever your instance can see. They don't draw any new posts in.
If you're on a new and small instance, you may find it useful to follow hashtag relays and topic-themed group accounts. These actively push all their content to all subscribers.
There's more about relays at https://fedi.tips/using-relays-to-quickly-expand-a-servers-view-of-the-fediverse/ and I'd specifically recommend the section on FediBuzz.
There's more about groups at https://fedi.tips/how-to-use-groups-on-the-fediverse/