URL availability report shows wrong SLA values for month June while the same report was working corrrectly for the previous month.
The June report was showing all URLs as having achieved 100% on the first page while the detail report had the correct data of the down time in minutes.
We created a clone off the SLA report having the problem and recalculated the problem report for the period of June 1 to July 1 activating the create historic data option. This then provided the correct data for the month.
The root cause of the problem could not be found. Neither could the problem be reproduced. I recommended to upgrade the product to the latest release.