Google has posted in the Google Search Console data anomalies page that they have lost about 19 days worth of data for any new Google Search Console user who signed up between June 21, 2017 and July 10, 2017.

Google wrote:

At least not all their users were impacted, just the new ones that tried to sign up between those dates. Of course, a lot of those users probably gave up trying to get data, so I do wonder if Google will be sending them a message about the issue?

At least Google is being transparent about the data loss.

Forum discussion at Twitter.