Facebook for Android app no longer displays og:image of website served via home computer's IP
I've tried installing the Facebook app on an a friend's Android phone and the images display fine there, despite the Android app on my phone, which is even faster, still doesn't display the image. This means the problem is a caching problem (e.g. I previously shared from my site while it had a bug, and the cached information is not being updated).

So, since I couldn't find a place where I could delete the Facebook for Android app's cache, I deleted the Facebook for Android application and all its data, and reinstalled it.

That fixed the problem.