Problem in exporting graphics from avogadro

avogadro version : 1.2
I have generated an electron density surface map using avogadro. input file format is fchk. while exporting the image using file -> export -> graphics , the resultant png file is coming distorted.
You can find png fle in following link:
https://drive.google.com/file/d/1P5UNITMJLHDkRi4MGhWbEH0K71UMU2ky/view?usp=sharing

How do I solve this?

Thanks in advance