Some people will never thank you. Lead them well anyway. The work was never a transaction.

Doing things for people in order to be appreciated works fine until someone does not appreciate it, and then it turns into resentment, which was always going to happen eventually. The alternative is deciding the behaviour is just yours: you help because that is what you do, and the response is not part of the arrangement. That is harder and much steadier. It also stops other people’s manners from controlling your character.

Do the thing once more this week for the person who never acknowledges it. Notice the urge to point it out and let it pass. If you genuinely cannot, that is worth knowing too.