marking this as Confirmed. just to summarize -

(1) it appears xlabel (and presumably y, z, etc labels) do not trigger any listeners to resize the plot.  making it obvious with a large font:

set(0, 'defaultaxesfontsize', 24);
subplot(1,2,1);
xlabel ('xlabel');

pushes the label off the bottom of the plot window. In matlab, the xlabel command forces a redraw so everything fits in the window.

It seems that a subplot command after this. a

subplot(1,2,2)

resizes both subplots so they fit with the xlabel.

this does seem specific to subplot.  if you replace the subplot command with, e.g., plot(1:4), the xlabel command will trigger a plot resize so things fit.

if apply xlabel after creating the second subplot, to either subplot, a vertical resize does occur.

subplot(1,2,1)
subplot(1,2,2)
xlabel('xlabel2')

subplot(1,2,1)
subplot(1,2,2)
subplot(1,2,1)
xlabel('xlabel2')

so, it seems the issue with xlabel not triggering a subplot resize only occurs with the first subplot?

(2) if you add a colorbar to the first subplot, colorbar triggers a horizontal resize to fit itself in the subplot space, but doesn't trigger a vertical resize, so the xlabel is still off window. 

set(0, 'defaultaxesfontsize', 24);
subplot(1,2,1);
xlabel ('xlabel');
colorbar;

a subsequent

subplot(1,2,2);
xlabel ('xlabel2');

only resizes the right subplot. the left one seems locked.


Unlike above, switching back to subplot 1 and then applying the label

subplot(1,2,1)
colorbar
subplot(1,2,2)
subplot(1,2,1)
xlabel('xlabel2')

does not trigger a resize.  colorbar seems to have locked the subplot size.

sorry. You need to add

set(0, "defaultaxesfontsize", 24) ;

to make it more visible, see attached figure.

Using

subplot(1, 2, 1) ;
xlabel("longitude") ;
colorbar
subplot(1, 2, 2) ;
xlabel("longitude") ;

shows that colorbar distorts the vertical positioning.