Google’s John Mueller said that data-href attributes are not links and thus do not pass link signals or PageRank. If you want it to pass link signals then use simple href link attributes. He said this on Twitter when someone asked if data-hrefs pass PageRank?
Global HTML data-* attributes are used to store custom data (ready to be called by CSS and Javascript). * is a wildcard that can be substituted by any subtitle. It is not a typical method of using hyperlinks, thus Google does not pick them up as links.
