The torsion-freeness conjecture for lbo homology

Let $X$ be a shelf, and let $H_*^{\mathrm{lbo}}(X)$ denote its lbo homology groups. Torsion-freeness conjecture. There is no torsion in $H_*^{\mathrm{lbo}}(X)$. The conjecture is suggested by the limited computational data discussed for lbo homology; no proof or counterexample is given in the source.