More than that, I find your assertion of the facts to be incompatible with the above stated assertion of the facts. You can't go from 1.4% to ~30-45% with only 11 states.
Somebody is playing some statistical games.
The 1.2% is the percentage of all white individuals in the entire country owning title to slaves.
The 30% to 49% is the percentage of white families owning slaves in given states.
Since each family at the time had an average of roughly five members, and slaves were heavily concentrated in particular states, it’s entirely possible.