xlabel not showing in subplot

%parameters for figure and panel size
plotheight=10.5;
plotwidth=31.5;
subplotsx=3;
subplotsy=1;   
leftedge=2.5;
rightedge=6;   
topedge=1.5;
bottomedge=1.5;
spacex=0.25;
spacey=0.25;
fontsize=5;    
sub_pos=subplot_pos(plotwidth,plotheight, ...
                    leftedge,rightedge,bottomedge,topedge, ...
                    subplotsx,subplotsy,spacex,spacey);
%setting the Matlab figure
f=figure('visible','on')
clf(f);
set(gcf, 'PaperUnits', 'centimeters');
set(gcf, 'PaperSize', [plotwidth plotheight]);
set(gcf, 'PaperPositionMode', 'manual');
set(gcf, 'PaperPosition', [0 0 plotwidth plotheight]);
CM=[0,0.4470,0.7410; 0.8500,0.3250,0.0980; 0.9290,0.6940,0.1250; ...
    0.4940,0.1840,0.5560; 0.4660,0.6740,0.1880];
%this is the data
data=xlsread('C:\Users\Madhur Mangalam\Google Drive\Write Ups\Papers\Ongoing\Mangalam_et_al._2018_Journal_of_Experimental_Biology\Fig6');

%loop to create plots
for i=1:subplotsx
  for ii=1:subplotsy
    ax=axes('position',sub_pos{i,ii},'Box','on','Layer','top');
    for v=1:1
      for h=1:3
        if i==h & ii==v;
          plot(data((h*4-3):(h*4),1:5),'o-',...
               'LineWidth',2.5,'MarkerFaceColor','auto');
          colormap(CM);
          if i==1
            axis([0.5 4.5 0 5]);
            ax.TickLength=[0.025 0.025];
            ax.FontName='Verdana'; ax.FontSize=12;
            ax.XTick=[1,2,3,4]; ax.XTickLabel={'Q1','Q2','Q3','Q4'};
            ax.YTick=[1.0, 2.0, 3.0, 4.0];
            ax.YTickLabel={'1.0','2.0','3.0','4.0'};
            ylabel('CV/UV');
            ax.YGrid='on';  ax.GridAlpha=[0.25]; ax.LineWidth=1.5;
            text(0.05,0.91,['\bf','A'],'FontName','Verdana', ...
                                       'FontSize',18,'Units','Normalized');
          end
          if i==2
            axis([0.5 4.5 0 5]);
            ax.TickLength=[0.025 0.025];
            ax.FontName='Verdana'; ax.FontSize=12;
            ax.XTick=[1,2,3,4]; ax.XTickLabel={'Q1','Q2','Q3','Q4'};
            ax.YTick=[1.0, 2.0, 3.0, 4.0]; set(ax,'yTickLabel',[])
            xlabel=('Quartile');
            ax.YGrid='on';  ax.GridAlpha=[0.25]; ax.LineWidth=1.5;
            text(0.05,0.91,['\bf','B'],'FontName','Verdana','FontSize',18,'Units','Normalized');
          end
          if i==3
            axis([0.5 4.5 0 5]);
            ax.TickLength=[0.025 0.025];
            ax.FontName='Verdana'; ax.FontSize=12;
            ax.XTick=[1,2,3,4]; ax.XTickLabel={'Q1','Q2','Q3','Q4'};
            ax.YTick=[1.0, 2.0, 3.0, 4.0]; set(ax,'yTickLabel',[])
            ax.YGrid='on';  ax.GridAlpha=[0.25]; ax.LineWidth=1.5;
            text(0.05,0.91,['\bf','C'],'FontName','Verdana','FontSize',18,'Units','Normalized');
          end
        end
      end                 
    end
  end
end
lgd=legend({'Chuchu - 2.1 kg', 'Dita - 2.1 kg','Presenete - 2.2 kg','Teimoso - 3.6 kg','Monsinho - 4.3 kg'},'Units','Centimeters','Position',[13.35 5.55 0 0]);
legend('boxoff');
lgd.FontName='Verdana'; lgd.FontSize=12;

print('C:\Users\Madhur Mangalam\Google Drive\Write Ups\Papers\Ongoing\Mangalam_et_al._2018_Journal_of_Experimental_Biology\Fig6','-dtiff','-r600');

[Image Analyst]

We have a different problem:

Undefined function or variable 'subplot_pos'.
Error in test (line 14)
sub_pos=subplot_pos(plotwidth,plotheight,leftedge,rightedge,bottomedge,topedge,subplotsx,subplotsy,spacex,spacey);

Please give us code that runs and illustrates the plot without an x label.

[dpb]

And immediately after the above problem will be we don't have the input file...

I suspect all that's needed is to remove the specific positions from the axes calls and use subplot and let it default to positions. You're probably just not leaving sufficient room for labels to show or are writing over the area the label requires to be visible with later calls to axes with fixed positions.