Mushy backstrap??

I just smoked some deer backstrap for about 3 hours at 180 bumped up to 210 for the last hour or so pulled at 142 deg, wrapped in foil with 2 tbs. Of beef broth let sit 45 min, then carved. the outside came out great the inside was mushy kind of like a liverwurst I threw a few slices on the grill and cooked until well done and it still had a slight pate texture.
Does anybody know why?? I have had a lot of venison in my day never had that texture
Thank you for the responses in advance