We cant guess your drive line, not now or ever.
so why ask. us?
my guess you mean the car drives in 1st gear but will not upshift,
and flares, in a false neutral.
wont and want is speed wrong 2 times, why?
Is car with TOD? torque on demand option, we cant see the dash board, we be like blind.
check fluild levels yet,
get the box serviced last decade, (a full flush and filter,) sure no.
check fuses, maybe car has TCM that cant up shift due to fuse blown.
and last did you scan it, if not why not
that be 3rd step after levels, fuses, then scan.
if the TCM cant see sensors, it cant upshift,
TCM is the tranny brain.