Turn on screenshots before creating an analysis and find out how pages are rendered.
Screenshots provided by Surfer will show you how the Google bots see your page. They have limits at 10k pixel height so you will see much more than in basic analysis provided by other tools.
The quality of your page and the responsiveness might affect your rankings, but often they depend on the device being used. To see what the problem could be, checking the screenshots might be able to provide you some insights.