Thankless means bringing no gratitude however well it is done. Notice it only when it goes wrong.
The classic phrase is a thankless task, and it usually describes work that keeps everything running and is invisible when it works, which covers a great deal of administration, cleaning and parenting. The word describes the situation rather than the people, so calling a job thankless is not accusing anybody. It is one of the most sympathetic words in English, because saying it to somebody acknowledges exactly the thing nobody else has.
1adjectivethanklessReceiving no thanks or appreciation, however well done.
“Chairing that committee is a thankless task.”
Middle English
thankles
English, today
thankless
From Middle English thankles, equivalent to thank + -less.
Etymology from Wiktionary, CC BY-SA