Posts work fine, the problem is in the Polls module.
If you try my UNA Poll again (https://unacms.com/page/view-poll?id=71) on the FB dev, you will notice that it picks up the wrong photo -very small blue background photo- (https://unacms.com/s/sys_images_resized/3hu76mwmvmrhujjs85vzrqrckhrhqy7i.png) which is not the cover photo of the poll. This is because the Og tags are not set properly.