On Twitter, Google’s John Mueller said that Google does not have exceptions for websites with broken headers and hreflang attributes.
A webmaster reported problems with an Akamai iframe that broke the header of the website. With that iframe, Google could not process the hreflang attributes correctly.
We don't have exceptions for sites that "can't make a clean head section", so you either have to fix it (maybe move it to the bottom of the head?), use a different method (headers, sitemap), or assume we won't always be able to pick it up.— 🍌 John 🍌 (@JohnMu) 12. März 2019
What are hreflang attributes?
If you have multiple versions of a page for different languages or regions, the hreflang tag enables you to tell Google about these different variations. Google then can point users to the most appropriate version of your page by language or region.
How to check the hreflang attributes on your web pages
Among many other things, the website audit tool in SEOprofiler also checks your pages for hreflang attributes. Create your SEOprofiler account now to check your pages: