Well if you haven’t over faced him then just use a dummy and work up to thicker cover ,,,
without trying sound like am trying to teach you to suck eggs , is there scent about on the ground /cover your trying to get him to enter ? As it will be easier to get him entering cover if something temps him in then once he realises that cover is where the game / dummy comes from he will start entering , think patience is the key , slowly slowly catchy monkey , try getting some scent on a dummy dragging it through grass in to thicker cover