The first ad I saw for it I thought "Oh this is going to be another one of their animated sci-fi movies that completely bombs at the box office and nobody likes it except for a small but vocal group of big fans who will call it underrated for the next 40 years."

They definitely did a shitty job of marketing it. Not one ad made any hint as to what it was about other than "three people in a weird place".

I'm guessing that with this and probably also Lightyear they figured the movies weren't going to do well anyway so they might as well save the ad budget for something else.