I tweeted a tweet and then checked the hashtag pages for it and saw it there. On the next day - it's only on one of them. And if I'm not logged in - it's not shown there either. Why?
This could be because the default filter/sort on Twitter search is "Top" and your tweet may not have enough faves/hearts and/or retweets to bring it up to the top of the listings.
It should show if you sort by "Live" which would show them chronologically (backward - newest at top) and not based on popularity (as weighted by the retweets and favourites/hearts mentioned).