A common term for people who do work well with others is team-player. So you could say:
Several co-workers who are not team-players caused the project to be delivered late.
If you want a term that is less perjorative, then uncooperative is, perhaps, the most straightforward word to use:
Several uncooperative co-workers caused the project to be delivered late.
Another possibility is individualistic:
Several individualistic co-workers caused the project to be delivered late.
If you want a term that describes the group as a whole, then incohesiveness is possible:
Due to incohesiveness, the team delivered the project late.
Alternatively, you could put it the other way round, and use cohesion:
Due to lack of cohesion, the team delivered the project late.