VB files : " indexed with language 'null' "


I’m trying to analyze a VB.Net solution with SonarQube from TFS with the TFS extension.
My issue is that when I activate debug log level, I see these lines for every vb file :

Somefile.vb generated metadata with charset ‘UTF-8’
Somefile.vb indexed with language ‘null’

This result is a successful build but the analysis result are just some random XML files analyzed and no vb bug or code smell.

Something interesting is that during the solution generation, a lot of logs that look like SonarQube warnings are present, leading me to think it is not far from working ?

Thank you in advance,