Strange lines and missing content in exported PDF, only at normal size, not when zoomed in.

When I export plots from Matlab, I see strange lines and missing lines. These are indicated by arrows in the attached picture. When I zoom in they go away. They also do not show up in print.

The trouble is, the document I am using these in will primary be viewed online. Users will not zoom in to see if the plot looks better. I want to make it look better at the default zoom level.

Any ideas how this can be accomplished? I am using export_fig

[Walter Roberson]

Which MATLAB release are you using, and which operating system?

In particular, R2014b or later makes a difference compared to earlier versions.

[Al]

2015a Windows 8.1 pro