The properties rticks and thetaticks also disappear on polar plots that are saved and then re-opened.

I pushed a fix for the first of these items (can't save colorbars when "tag" property is used) to the stable branch that will be released very soon as Octave 9.1.  See https://hg.savannah.gnu.org/hgweb/octave/rev/9cb993582499.

Great software, it is incredible what Octave has grown into.
Three related (I think) bugs to colorbars:
1. When an axis with a 'tag' property is saved using hgsave and it has a colorbar, the colorbar is not recreated when using hgload.

2. When an axis with a colorbar is saved with hgsave and reopened with hgload, changes to the colormap and color axis limits are updated on the main axis but not on the colorbar axis.

3. Any callbacks aren't saved using hgsave

I would expect a figure opened with hgload would be identical to when it was saved both visually and functionally (including buttondown callbacks).

I think all three issues are related to the hgsave function and how it parses the existing figure, which I why I grouped the three items together.

I'm using Windows 10, 22H2
Octave v8.4.0,"x86_64-w64-mingw32"

Code reproducing issues below.

%Minimum working example to demonstrating
% 1. The colorbar is not saved using hgsave if the main axis uses the 'tag' property
% 2. When opening a saved figure with a colorbar the colorbar is no longer linked to
%    the main axis when using caxis or colormap functions
% 3. Callbacks aren't saved using hgsave, so when figures are reopened they do not
%    function the same as the original figure

[x,y,z]=sombrero();
hfig=figure;
hax=axes(hfig);
set(hax,'tag','sombrero');  %Tag to find axis easily later
hsrf=mesh(hax,x,y,z);
hcb=colorbar(hax);
colormap(hax,'jet'); %Both plot and color bar adjust appropriately on new figure
hgsave(hfig,'color_bar_test.ofig');

%open saved figure
hfig2=hgload('color_bar_test.ofig'); %New figure opens, missing colorbar

%If we do everything the same but don't use tag property colorbar is saved
hfig3=figure;
hax3=axes(hfig3);
%set(hax3,'tag','sombrero');  %Tag to find axis easily later
hsrf3=mesh(hax3,x,y,z);
set(hax3,'buttondownfcn', @(h, e) disp ("Button Down Callback"));
hcb3=colorbar(hax3);
colormap(hax3,'jet'); %Both plot and color bar adjust appropriately on new figure
caxis(hax3,[-4,4]);  %Axis limits and legend update, :)
%Clicking on the axis of figure3 display 'Button Down Callback'
hgsave(hfig3,'color_bar_test_notag.ofig');

%open saved figure
hfig4=hgload('color_bar_test_notag.ofig'); %New figure opens, with colorbar
%Try to change caxis limits
hax4=findobj(hfig4,'type','axes','xlimmode','auto');  %Color bar has manual xlimmode, use this to find sombrero axis
colormap(hax4,'winter'); %Colorbar does not update, no longer linked :(
caxis(hax4,[-1,1]); %Axis limits also not linked anymore :(
%Clicking on axis of figure4, no callback is fired or even exists
missing=get(hax4,'buttondownfcn');  %Callback is empty, not saved :(