Desktop version Portrait view on ipad screen blank except for hook

I have spent so much time trying to figure this out. I am not a total newbie, but by no means a Wordpress or coding expert!

When GP Premium is activated, and go to Desktop version on an Ipad, the Portrait view is blank screen except for the hook in the header, when turned to landscape it views OK.
When change to Mobile version all works fine.

When I deactivate GP Premium, view comes back for desktop view.

Unfortunately when deactivated, it causes other issues eg the header hook does not show up, and other customizing is changed.

I have gone into my Simple css editor, and changed max-width to 767px, (as well as trying other widths: also changed it in mobile.css as per instructions when searching for help.

Any ideas would be appreciated.