I hav ethe following problem: When I share a link to one of my blog pages to google plus, google plus loads the first image in this article as featured image. Facebook does the same.
Also you i can see the difference between image format .png and .jpeg which can cause this.
I have tested sharing the post URL on my Google plus profile which doesn’t show image on your shared Google plus profile and found it’s working fine as shown in the attached screenshots so could you please try sharing it again?
I checked your Google+ profile on iPhone 6 Plus, Galaxy S5 Mini and iPad Air and featured image appears to show perfectly fine. My guess is that it is some local problem with Google+ app. But since everyone else can see posts and images you share it shouldn’t be a big problem.
I will check if other Google+ users have noticed the same problem with featured images and will let you know in case I find something useful.