All Backlinks Removed on Google Webmaster

I built my website in November 2016. I built some backlinks from November to December . I have left the link building since January 2017 because I was very busy.

I checked today now and discovered all my backlinks on Google Webmaster have been removed. For the experts on this forum, What is the cause of this?

Bug - multiple threads, check here too productforums.google.com/forum/#!topic/webmasters/kHGfiVjTRPM