Doesn't work when selecting articles manually

I’ve tested this on a few different sites, using different themes and on different servers.

When using the Yuzo post options metabox on the post edit screen, and manually selecting posts that should always go with the post, the plugin has some issues. It selects a random image that may or may not be attached to any post and adds it.

Here’s an example screenshot where I manually selected two posts using the metabox and a random image was added as well:

https://cloud.githubusercontent.com/assets/4042621/13731838/304e7892-e941-11e5-8a8c-f22485c3dc6f.png

http://theforestscout.com/2016/03/01/five-minutes-with-bulls-coach-fred-hoiberg/

https://ww.wp.xz.cn/plugins/yuzo-related-post/