Problem displaying tick values [SEC=UNCLASSIFIED]

Hi,

I have just upgraded Python, matplotlib etc. After this matplotlib is
having trouble displaying tick values. Values that only require one
character are displayed fine but other values (e.g. -1, 1.5, 10 etc.)
cannot be displayed. Boxes are displayed in their place.

I tried changing the tick font and the size of the font but this did not
help. Putting multiple digit values in the x-label works fine.

Any suggestions?
Thanks,
Damien

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