Abnormal HistPdfs when composed by 2D histograms

Dear RooFit experts,

I experiencing strange behavior when I compose a PDF by using TH2 histograms.
It looks like RooHistPdf don’t work properly when 2D histograms used while it works for 1D.

There was a similar bug in past, but it was confirmed to be fixed at that time:

The attached figure is same 2D PDF’s projection to each variable:

  • For top 2 plots, I projected a 2D histogram into each direction,
    then composed each HistPdfs, then again composed a whole 2D HistPdf by using 2 HistPdfs.
  • Bottom 2 is exactly same PDF but I composed it by using 2D histogram directly.

I checked same behavior happens in RooFit version 3.17, 3.56 and 3.59.

Could anyone check if this is a bug or nor?
I also leave my code used to make this plot.
HistPdfTest.C (2.04 KB)