In a post on the Google data anomalies page, blocked resources report within the Google Search Console may have incorrect data being reported over a three-week period.
If you pulled any report between January 16, 2018 and February 22, 2018, Google said that “users may see decreased counts of pages with blocked resources. This is due to a processing error on our side. Page counts should return to their correct levels within a few weeks.”
The following is a shot of this report. Notice that the vertical line that says “Note” which specifically documents this reporting issue: