It took months before the first mention of Section 3 in a public document. Free Speech For People, a Massachusetts-based liberal nonprofit, sent letters to top election officials in all 50 states in June 2021, warning them not to place Trump on the ballot should he run again in 2024 because he had violated the provision.
None of them took action, part of a general silence in reaction to the group’s arguments.
“People were just treating it as something that was not serious,” recalled John Bonifaz, the group’s co-founder.
By January 2022, the group decided to test Section 3 in court.
Looking for a lower-level defendant, Sherman’s organization zeroed in on Couy Griffin. The subject of one of the earliest Jan. 6 prosecutions, Griffin already has a rich legal record. He was was recorded in a restricted area of the U.S. Capitol as head of a group called Cowboys for Trump. Griffin was convicted of illegally entering the Capitol, but acquitted of engaging in disorderly conduct.
He still served as a commissioner in a rural New Mexico county, which kept CREW’s attention on him. On Sept. 6, 2022, a New Mexico judge ordered Griffin removed from his position. It was the first time in more than 100 years an official had been removed under Section 3. Griffin has appealed to the Supreme Court.
Unfortunately, the lay definition of "officer" isn't the same as the Constitutional definition. Also, the entire phrase "officer of the United States" is not the same as the positional title of just "officer."
The Constitution refers to "officers of the United States" more than once, but each time (excepting the Fourteenth Amendment) they're described as positions appointed by the President. The theory is that since the Constitution refers to them as appointed by the President, the Presidency itself cannot be an officer of the US since the President is elected.
Here's a law article from Seth Barrett Tillman explaining that position. (Page 21 is where the relevant argument begins.)