That FEX submission hasn't been maintained in over a decade and predates the current graphics system. It doesn't work unless you rewrite parts of it to fix all the things that have either broken since 2011 or things which have never worked well to begin with. On the submission page, there are multiple suggestions from users regarding ways to work around those problems, including ways to address the unusable low-resolution raster output option. I would suggest to either try one of those, try to increase the specified resolution, or use something else.
If you want to continue trying to troubleshoot applyhatch_pluscolor(), you'll have to provide a complete example of how you're using it. If you've modified applyhatch_plus.m or applyhatch_pluscolor.m, you'll have to attach them, otherwise nobody else can be sure they're replicating your conditions.
If you choose to use something different, depending on what you expect, hatchfill2() on the FEX might work as well.
That will modify the contents of the figure itself. If you then want to save the figure, you can do so using whatever method you choose. (e.g. manually using the figure/axes tools, programmatically using print(), export_fig(), or in newer versions, exportgraphics())
