It’s hard (impossible?) to say why this would happen on a given team because it’s all so contextual. However… my gut says 80%+ of the dysfunction is rooted in trust and psychological safety issues. The other 20% might have to do with team members coming in from disparate teams (each with their own reporting manager, each of whom, in turn, have different goals or are incentivized differently). Essentially, a case of conflicting priorities. Or, perhaps the trust issues are actually a result of the conflicting priorities issue.
A colleague of mine recently published a piece about “the Hollywood effect” (the trend towards cross-functional teams that form, deliver, and disband in under a year) that touches on some of the gotchyas you raise here: reporting relationships and decision-making, especially. Maybe that would provide some insights or color. https://venturebeat.com/2017/03/05/form-deliver-disband-the-power-of-temporary-innovation-teams/