I think our mount design is pretty sub par. I have the AWR because my stock mount was so bad at times when I shifted too fast from 1-2 or 3-4 I would grind slightly. I swapped out my stock mount for the AWR and it was good for awhile, but now that that mount is broken in every once in awhile the same will happen. Obviously if the engine is lashing around or is not at the proper angle while shifting that is going to affect shifting performance. The engine might be tweaked enough so that the shifter cable cannot extend into gear fully or engage the gear properly.
With that being said just modify the plate on the TMIC, or get a rear mount that will help.