Google’s Search Console, formerly Google Webmaster Tools, is having a data issue with their Search Analytics report. Data for July 28 is missing from the report, and there are widespread reports of the issue.
Although not everyone is affected, I am able to replicate the issue across my account. If you scroll over the Search Analytics chart, you will see it skip from July 27 to July 29, completely missing July 28.
I created this animated GIF showing the issue:
Gary Illyes from Google told me that Google is aware and is working on fixing the issue.