google mobile friendly test - not working for nop?

I am also seeing this problem, and Google Webmaster Tools is complaining that mobile usability issues now occur on over 1000 pages!

The test passed perfectly last week, but it now renders the desktop version of my site.  Any insight would be appreciated!

Same issue here, if you enable the mobile theme from administration you will get flagged by Google and your ranking will take a hit.  It has made that feature useless.  It may have something to do with the googlebot user agent. Until someone can come up with an answer all nopCommerce users should migrate to a responsive theme I guess, I'm not looking forward to the time and cost of that.

I was wondering if it had something to do with the "force desktop" cookie being set on the Googlebot itself.

I have created a link at the top of the mobile site which gives users the option of using the desktop site instead, but I hadn't included a rel="nofollow" on this link, so in theory Googlebot might have tried to follow the link during its indexing process and forced all subsequent requests after this to the desktop site (making it ultimately fail the mobile friendly test).

Does this seem feasible?  And if so, what can we do to correct it?!

Also, if you have a responsive theme installed you will pass the test even if a mobile theme is installed since Google sees it as the desktop version.  If you don't have a responsive theme, you will fail the test no matter what.  We have 2 stores with different themes on the same site.  One passes the test, the other does not.

But is there a "force desktop mode" link somewhere on the site which is failing?

Google doesn't force people into a responsive design - a design which adapts to serve a mobile-specific theme should work fine.

Has anyone confirmed that google is no longer considering the mobile version of a website, and requiring responsive? I'm curious if this is true, versus if google mobile bot is just not triggering the mobile theme?

The best place to ask (or report) this is Google Product Forum for Webmasters

Google is not forcing responsive design.  If you have a responsive design on your non-mobile theme, then you are okay because that's what Google is testing.  If you don't, as is the case for one of our regular themes, then Google doesn't see the mobile theme (even though devices do) and flags it as not friendly.

I think this is because Google's test DOES follow a link to the desktop site and I have a solution that appears to be working:

Use Google's test to browse the URL which explicitly sets it to mobile mode (e.g [domain]/changedevice/false)

This should cause the test to pass.  Once this is done, any subsequent tests on the root of the domain appear to pass.  I would still recommended adding a rel="nofollow" attribute to any link that allows the user to override the automatic device detection logic.

Hope this helps.

This article seems to indicate that a vary header could fix it- https://developers.google.com/webmasters/mobile-sites/mobile-seo/configurations/dynamic-serving