I first notices this problem a couple of weeks ago and opened a support ticket about this a week ago. The blog page archive (content) is not visible on iPhone and iPad and took a while to appear on desktop. It seems to be a conflict with the SG Optimiser Plugin. When I turn it off, the content is displayed. I’m reporting this to you but I’ll also report this to SiteGround.
I can see that when the browser view is around 800px wide because there is not enough room for the menu and the logo. If that is the same for you then you can use the CSS provided here to break to mobile earlier: