hreflang tags?

Questions about hreflang tags of pagespeed tools and multilanguage sitemap plugins.

My site: xxxxx.com used to have hreflang tags in version 3.8 with your pagespeed tools.

Since upgraded to 3.9 or 4.0, hreflang tags not detect in Google search console anymore.

I tested with other tools and none detected.

I downloaded latest version and still not work.

Do you know what may cause the issue?

Your pages had this tag.

See attached picture.

this is code from your page

<link rel=alternate href=http://xxxx.com/en/nails-supply hreflang=en>
<link rel=alternate href=http://xxxx.com/vi/san-pham-nghe-nail hreflang=vi>

HTML 5.0 standard allows to use tags without ".

You tried to check hreflang using external online service but the developers did a mistake. They wants to check this tag with ".
Google can read this tag from your pages.

Don't worry.

Use this service
http://hreflang.ninja/check/