Joed, are you running your loco in conventional mode? I have two Lionel and one K- line loco equipped with TMCC that start abruptly in conventional (I haven’t run them in TMCC). Two of them have Odyssey; they start OK in that mode, but run erratically thereafter, so I shut Odyssey off.
The experts will probably refute me, but I suspect the abrupt start is normal when running Lionel engines conventionally.
John