What's the term for the phenomenon "people in a team can't say 'no' because they are in a group"?
Is peer pressure the phrase you're looking for? While it can also mean someone directly pressuring their peer into something, I believe it covers your example of pressure to agree with the group.
(I just saw that you answered your own question with "the Abilene paradox" so if this is irrelevant now, feel free to ignore it.)
I found the term - It's called the Abilene paradox: In the Abilene paradox, a group of people collectively decide on a course of action that is counter to the preferences of many or all of the individuals in the group.
