It was announced today that Miller's loan at Huish Park, which was meant to last until the end of the season from Nottingham Forest, had come to an end a month early.
Johnson explained that Miller walked out of a meeting after he had left training claiming that he was "stiff".
Speaking to the club's official website, Johnson said of Miller: "He is no longer with the club. To be fair I don't think his personality and football personality are conducive to our environment.
"We had a meeting on Tuesday. We wanted to ask people why they were going home when they were stiff. I asked a couple of people and I got around to Ishmael and he was disappointed I brought his name up.
"He didn't want to get involved in a discussion and he ended up saying 'okay, I don't want to play for you'. He walked out of the room. That was the third time and we can't let that happen."