Google has posted a “note” in the Google Search Console of “an internal logging issue” which may cause the numbers in the Search Analytics reports to “see a very slight decrease.”
The issue is between August 14th and August 15th and reads:
Users may see a very slight decrease in numbers due to an internal logging issue.
It is unclear if this is related to the delay in the search analytics data from last week, continuing on or not.
So if you see weird data on those days, you are 100% not alone.
Forum discussion at Twitter.