In my experience working with elite athletes and seeing dynamics played about between the Athlete-Coach relationship, or overall sports teams and entrepreneurs I've consulted, Great teamwork should be fostered in an environment of open-mindedness and a mandate embraced that idea-conflict is healthy, but personal conflict will not be tolerated.
Too often though weak leaders, or uninformed leaders, believe their teams must all become friends with one another and they attempt to force this camaraderie rather than let it develop naturally.
More specifically, early symptoms of unhealthy personal conflict include members needling one another behind the other's backs, negative body language (one of the most relevant signs, after all it's difficult to hide in a workplace), and a third symptom whereby one begins to repetitively shifting blame toward the other for even the smallest of tasks not being fulfilled - or perceiving the task as being completed at a level not to their satisfaction.
Feel free to ring me for an initial consultation...the beginnings of a fractured team dynamic will certainly be detrimental to the overall success of the teams goals. This is a topic I've dealt with many times in my career, and I'd be happy to provide you with actionable steps to resolve the issue and provide immediate steps to rally the team so you can achieve your mandate.