Indeed. The search function is mostly intended for title and tagline searches. If you want to search by tags, it's best to use the actual tag system. Free text search kinda-sorta works on tags too, sometimes, but as you've seen is unreliable.
Ok, so how can I use/improve tags to make my game update be visible? What's "the actual tag system"? I'm using game tags and I'm searching through "Select a tag", not "Search for games and creators", which is not the best choice for tag search.
I've just tested it again using "nsfw" tag in the "Search a tag", narrowed the search to 7 days and 1 day - my game is not showing up (it has "nsfw" tag). Two other games, which were posted 1 day ago and 1 hour ago are on the list. So what can be done about this?
I remember my game being on top after the previous update a couple of months ago and it moved down as other games and updates got released by other creators. Has something changed and newly updated games don't appear on top of "Most recent" and "New&Popular" and stay at the bottom?
Maybe an updated game is given less of a boost than a brand new one, I don't know. But it's also that a lot of new games come to Itch.io all the time. Older games also bob up and down in search results, so that everyone gets a chance. Yours may make it to the top again later, too.