Labels placed incorrectly in pst-jtree

When trying to draw a tree with pst-jtree, the node labels end up all stacked on top of each other. The following code (which requres xelatex) should place the labels at the terminal nodes:

documentclass{article}
usepackage{fontspec}
usepackage{pstricks,pst-xkey,pst-jtree}

begin{document}

jtree
! = {}
:{X} 
:{Y} {Z}
.
endjtree

end{document}

Instead the result is this:

This happens on several other installations too, after having worked for years. Any idea what the problem is? Here is the log with /listfiles added. It shows the following:

*File List*
 article.cls    2020/04/10 v1.4m Standard LaTeX document class
  size10.clo    2020/04/10 v1.4m Standard LaTeX file (size option)
fontspec.sty    2020/02/21 v2.7i Font selection for XeLaTeX and LuaLaTeX
  xparse.sty    2020-10-27 L3 Experimental document command parser
   expl3.sty    2020-12-03 L3 programming layer (loader) 
l3backend-xetex.def    2020-09-24 L3 backend support: XeTeX
fontspec-xetex.sty    2020/02/21 v2.7i Font selection for XeLaTeX and LuaLaTeX
 fontenc.sty
fontspec.cfg
pstricks.sty    2020/06/11 v0.70 LaTeX wrapper for `PSTricks' (RN,HV)
   iftex.sty    2020/03/06 v1.0d TeX engine tests
  xcolor.sty    2016/05/11 v2.12 LaTeX color extensions (UK)
   color.cfg    2016/01/02 v1.6 sample color configuration
   xetex.def    2020/08/26 v5.0i Graphics/color driver for xetex
pst-xkey.tex    2005/11/25 v1.6 PSTricks specialization of xkeyval (HA)
pst-xkey.tex    2005/11/25 v1.6 PSTricks specialization of xkeyval (HA)
 xkeyval.sty    2020/11/20 v2.8 package option processing (HA)
 xkeyval.tex    2014/12/03 v2.7a key=value parser (HA)
pstricks.tex    2020/09/18 v3.01 `PSTricks' (tvz,hv)
  pst-fp.tex    2020/09/18 v3.01 `PST-fp' (hv)
pstricks-xetex.def
pst-xkey.sty    2005/11/25 v1.6 package wrapper for pst-xkey.tex (HA)
pst-jtree.sty    2011/01/04 package wrapper for pst-jtree.tex
  ts1cmr.fd    2019/12/16 v2.5j Standard LaTeX font definitions
 ***********