For two of my websites there is something weird happening:
1 - In the evolution graph (Visits over time) I can see the same number of Pageviews for two different days (2017-10-28, 2017-10-29). I already deleted the data in the archive_numeric_2017_10 and it was recalculated, but it shows again the same value (over one hundred thousand, so, it is practically impossible they can coincide).
2 - The Visit per server time report for yesterday (2017-10-30) is not complete, the data is being built according to the evolution of the actual day (today), and it is showing the same data than today. I deleted the blob record of the report (VisitTime_ServerTime) and ran core:archive. After all that, it keeps happening the same thing, it shows data for the actual hour, acting like if yesterday was today (today is 2017-10-31 and I'm talking about 2017-10-30).
There was a change from summer time to winter time, both sites use Spain timezone. I believe that the hour adjustment caused the problem with Piwik logic.