The Google data anomalies page has been updated to document that there was a data loss within the Google Search Console tool for new users who signed up between June 21 and July 10, 2017.
These webmasters and SEOs who signed up to the Google Search Console and verified properties won’t see those 20 days of data. It seems that Google fixed the issue going forward, but if you are one of the ones who signed up as a new year during that date range, you’ll miss data between those dates.
Google wrote:
All first-time Search Console users who joined Search Console during this period will be missing site data during this period. First-time users who joined before or after this period are not affected.
Anybody who signed up to the Search Console before or after those dates, you won’t be impacted.