The spin density matrix element (\rzz) as a function of \fnonprompt in $5<\pt<7 \GeV/c$ for charm- and beauty-enhanced samples obtained for minimum-bias and high-multiplicity triggered pp collisions at $\s=13 \TeV$. Only statistical uncertainties are shown. The blue line represents the linear fit to the data with the blue band indicating its $1\sigma$ confidence interval.