Quote from OW Visuals
It is because you need to put your image in to the ow_themes/your_theme/images folder

Thanks!

Hate the heart.  Really. Hate. That. Heart.   Great theme, but I'm not running a chick site.

David, how I changed it was I downloaded the current .svg loaded it into Ai saved it as an Ai file then loaded that into photoshop. Once there I made my own, saved as PSD, loaded that into Ai, then exported it as .svg again. Then upload to server.

Yea, the heart was a really an odd choice for a icon. I replaced mine with a check mark and a thumbs up icon.

The default theme I will say has gotten a lot better then the original one. My only other gripe is that it's not a true responsive theme, I hope they fix this in the future.

I got mine changed to the thumbs up "like" using simple line icons. I edited it using inkscape. Inkscape is a freeware available on cnet downloads. They also have a site with lots of info. I would attach the file I created, but it doesn't allow .svg attachments.

Since I can't attatch my svg file. Here is a detail step by step on how I did mine. with a screenshot of how they look. The icon image screenshot was where I was preparing them for the venus theme.
You will need to replace the file on each theme update. I couldn't find any way of doing this through custom css in the admin panel. There may be some script dependencies that are specifically calling for the miniic_set.svg file.