Another reason you might be struggling to communicate is because something painful happened in your relationship that hasnt been fully resolved. Perhaps there was a betrayal or someone said something thats never properly been amended.

What causes poor communication skills?

It ranges from: Ego. Attitudes towards others on the team, be it regarding gender, ethnicity, education, religion, childhood issues they are harboring, etc. Bottom line is that ego issues are one of the biggest challenges I see amongst leaders that have bad communication.