It is impossible to find a game because I am a coach of the group without the participants.
If you coach a group and the group disbanded, it is impossible to find a solo game because the game thinks that I am the coach. For single player no check button to off coach mode.

Screenshoots (sorry, I have a russian game client):
I'm not in a group.
Dota say: "Error. Уou cannot search for a game with such a composition. To search for games in the group must be more players than trainers."

Merry Christmas.