Amy Tanner Thiriot notes the lack of slave registrations in Utah.
Amy Tanner Thiriot, Slavery in Zion: A Documentary and Genealogical History of Black Lives and Black Servitude in Utah Territory, 1847–1862 (Salt Lake City, UT: University of Utah Press, 2022), 20-21
The Utah State Archives holds slave registrations for Shepherd, Daniel, Jerry, Caroline, Tampian, and Lucy... The registrations refer to a book called Probate Register of Servants, but it does not appear to exist anymore. None of the registrations indicate that Judge Elias Smith questioned any of the six about their desire to remain in servitude.
Due to its attempt to treat slavery as contracted labor, the Act accounted for few of the situations normally encountered in Southern slavery. It was not a cohesive slave code with principles familiar to Southern enslavers, and they and the probate court mostly ignored the Act and its provisions. Although John Brown was a member of the first territorial legislature, there is no record that he or Elizabeth Crosby Brown registered Betsy in the probate court, and the price he listed for Betsy in 1857 of $1,000 was a high price for a chattel slave of her age and sex and did not take into consideration any limitations on his ownership of her and her future children.