I noticed a problem concerning TH2 objects.
When I save in root 5.20 a TH2D histogram into a C-file the histogram-object is saved in the C-script as a TH1 object. Anyway, since TH2D is a daughter of TH1 it is not a real problem as long as you do not try to use a specific TH2D function (as ProjectionX() for example).
i.e. in the saved C-script the histogram-object is called
In my case - for bringing ‘ProjectionX()’ back to life - I changed in the C-script TH1 to TH2(D)