My SSL Certificate on HTTPS Protocol was working fine and showing green bar. But after installing GP theme its not showing green bar and message showing content not secure. Whats the issue is there any non ssl links in theme?
if you open the HTTPS site in Chrome, right click > browser inspect and check in the Console you will see a few mixed content errors, none of which seem to be GP related. You can try rebuilding permalinks or re-adding those assets.