190mm seems an odd size for T&G? If you used a plain softwood board to make up the gap in the floor then I am not surprised it cracked eventually. Simple solution might be to replace it with an appropriate thickness ply. Personally as the pipes should be towards one wall of the room approx. one quarter of the joist length maximum from the wall then I would be tempted to rip the T&G up to the wall and re-lay it from the last board trimming the final board up to the wall.

Richard