Do you have Facebook app installed and active on mobile? Can you click Facebook icon and get to your account without logging in? If you login each time on mobile to visit your account, you will be required to login to share this or that product, please try to share anything else beyond your site to test.
Please provide your site admin access to the private area as well as screens of what you want to change.
Yes I have FB app installed & already logged in it. When clicked on facebook share icon, its still sending me to browser. I also tried share post from other sites, some of them worked some them sent me to browser.
Also we are using this theme for our multiple websites. Same behviour is there. You can check on below site also.