Themes suddenly provide mobile version only 

I run two websites with Elmastudio themes: http://www.vivabritannia.de with Pohutukawa and http://www.psycho-talk.de with Tatami. After setting up a new iMac I noticed that I could only get the mobile version to show on the Desktop, both in Safari and Chrome. Also, when someone on iOS devices tries to force loading the desktop version, nothing happens either. Today I checked other sites using Pohutukawa and Tatami, and it’s the same. Any suggestions how to get the desktop versions back? (Suffice to say that I haven’t changed any website settings recently).