It appears that some schema markup appearing in the mobile search results is forcing the “Mobile-friendly” tag from being listed in the search result.  Steve Morgan from SEOno was the first to publicize the issue.

However, when you check the URL and the page in question, it both appears to be mobile friendly and passes Google’s mobile friendly test as well.

Because the sites are still mobile friendly, despite the missing tag, they should be still getting their mobile friendly ranking boost.

Other schema markup, most notably the date from a page, does not remove the mobile friendly tag, but appears after it.

This does seem to be a display issue of sorts, so it does not appear to impact these pages getting their mobile friendly ranking boost in mobile search results.

Grant Simmons commented at SEOno that the issue is also affected Homes.com and he discussed the issue with Maile Ohye at Google several weeks ago, and received this response from Ohye:

“hi grant! thanks for the example. turns out our engineer is aware of this issue — currently the mobile-friendly badge can be trumped by a few other UI cases: pagination, “jump to” app links, and video thumbnails… fyi we may change the display and have the mobile-friendly badge override the other conditions. he’s going to look into it further.”

So if you are currently utilizing schema for these types of features, you will need to decide whether it is more important to have the “Mobile-friendly” tag or potentially have it removed for pagination, app links or video thumbnails.  If you prefer to have the mobile friendly notation, you should remove the markup for the other types of rich snippets that would override it.