Biggest teamwork fail? This is the general way we do business where I work right now:
My boss didn’t want to be the kind who hovers, always micromanaging. He also hates the idea of taking programmers away from their work for meetings. Sounds great, right? This has resulted in:

• All non-lead devs being excluded from all meetings other than scrum (including sprint planning and review meetings). Nobody ever knows what the hell is going on. They don’t think we “need to know.” This means most of our day is spent trying to figure out what needs to be done, rather than getting anything done.

• Our remote boss making dozens of important decisions about our platform, never telling us, and blaming us for not forcing our lead to be more communicative.

• Pull requests staying open for weeks, sometimes months, because nobody has definitively decided what version we’re actually supposed to be working on. This means our base branch could be any of them, and it means PRs that have been opened too long need to be closed, updated, and re-opened on the false promise of someone actually looking at it.

Just ranting here... but I think our biggest teamwork fail is happening right now, with all of those things ^