On my main account, a child account, I can't chat to my friends or any other players, but I can see my message and their messages.
So on my adult dummy account, I looked up on my main account confidentiality and privaty settings only to check if every options was on everyone and it was! No issue from the parental account.
On xbox companion, I could chat with my friends just as normal, but not on minecraft Windows 10. I contacted microsoft chat customer service and everything looked fine from xbox end. So they thought it may be an issue from the game itself.
To makes things clearer, I see my own message and see theirs, but they just don't see mine!