"Share" button does not appear in LinkedIn post

I've set up my blog posts to share to Facebook and LinkedIn automatically. Both social sites are set to display on the blog post title; %t. The posts to Facebook are perfect, going to the correct account and fully shareable. LinkedIn posts only display the post title and the "Share" button is not displayed. The posts. The posts are not public and are only viewable by my connections. The purpose of our website is to draw attention to our son's kidney disease and his need for a live donor for transplant. If I can't make the LinkedIn posts public and shareable, the "Share" feature in the blog posts is useless. While the Facebook share works flawlessly, it will have a much smaller reach. Posts I shared manually on LinkedIn are getting thousands of impressions in a matter of days. Some posts have been reposted up to 50 times, far more than Facebook shares. Any and all help on this is appreciated.