Hi,
I'm not sure but maybe is not an unussual problem, but maybe not for the same reasons... let me explain...
During more than 20 days MJ works (only detects if user connects from an android or iphone, and in thes case the menu is diferent) so, works excellent...
but today also from a desktop goes to mobile menu. The only way to solve i disable the mobilebot plugin. really strange... but, one thing that maybe an expert can considere: 1st. before this problem is it possible that one user connect from a desktop but using an iphone as modem (by cable).

Well it's really strange for me, I've readed some post in ther forum about this situation but no one solve my case

MJ saves current site mode in cookies, so clear cookies or visit yoursite.com/?device=desktop to reset mode to desktop.

i have the same problem. and when i use yoursite.com/?device=desktop as suggested, i see the desktop version again. 

but the mobile menu reappears when i type the usual url.