MusiXTeX beam slope rendering problem

I have the following code

\documentclass{standalone}
\usepackage{musixtex}
\begin{document}
\setstaffs1{2}
\setclef1{6000}
\startextract

\Notes\Qqbl JMRM|\ibl0i{-1}\ztqb0{il}\sk\ztqb0{jm}\sk\ztqb0{il}\sk\ztqb0f\qb0i\en

\endextract
\end{document}


That renders like this

What should I do in order to make it like this?

I have been reading a lot but have had no success in finding an example with code nor anyone with the same problem

• If you don't mind the slope, reduce\ibl0i{-1} to \ibl0i{0}, the corner is cured. Otherwise please waiting for professional answer. Apr 21, 2020 at 6:12

\documentclass{standalone}%