Hi,
I believe this is the same issue as in this post. For convenience I will copy the answer from the other post:
"This seems to be a display issue. Can you try this out and let me know if it works:
Right-click on the pix4dmapper.exe file,
select the Compatibility tab and
enable ‘Disable display scaling on high DPI settings’: the checkbox below should be checked.
Let us know if that solved the problem. Thanks!