Jefferson was pretty much an economic failure, as a plantation owner. Washington manumitted his slaves in his will. Jefferson died in debt, and his debtors would not have allowed it.
Jefferson did some manumission - “dropping the ball”, if you will, intentionally with some slaves and “letting them fall through the cracks”. That is manumission. Freeing on the sly with no one knowing. But, supposedly he did free a few slaves in his will. Probably his favored people.