Five keys to a successful team

"The value of a whole group is higher than the sum of the individual values" - Aristotle The most important part is the psychological Safety, where team members feel safe to take risks and be vulnerable in front of each other

The key dysfunctions are:

Absence of trust with colleagues

They have to feel comfortable being vulnerable in front of each other with no filters.
Make an afterwork small session where each of the members of the team share a personal vulnerable story in front of each other. As a manager you need to lead with example breaking the ice. Knowing each personality is a good previous starting point. Team buildings are okay but are more superficial.