The 25-year-old failed to make the squad due to lack of fitness after recovering from a torn ligament injury.
The Ghanaian has been training with the German second-tier side for two weeks and wad declared fit to play last week.
But he was left out of the squad as the side drew 1-1 at Ingolstadt and coach Tim Walker has explained the circumstances.
"There are always training impressions that you collect. It's crucial to accelerate in training, "Walter said, adding," He was not in the squad because the others did a better job. There was lack of training.
Sport Director Fabian Wohlgemuth jumped to the defense of the coach amid reports his comment was itended to incite the player.
"Being patient in such a situation is certainly a challenge for every player. I am sure that Kingsley gives himself the necessary time and deals with it professionally."Wohlgemuth said.
Kingsley Schindler has been linked with a move away from the club this summer.