1450 only? Denny have you had issues with this yeast above 22.5P?
my impy stout stalled at exactly same point. took 3 days to ramp up and finish out though, just had to warm it up again.
OP did you use nutrients? That is what I had to throw to help encourage my brew to finish, but I used dual strains. Partially because the 1450 was a little old too.