Hi, @Asad. Thanks for being patient while we looked into this.
For reference (especially for others who might come across this post in the future), this daylight savings time (DST) info for Santiago is useful. The standard offset for Chile is 04:00:00Z. During DST, this changes to 03:00:00Z. In 2016, DST ended on 2016-05-15. It started again on 2016-08-14, as you mentioned.
You are correct that the INVALID_TIME_WINDOW error is returned for any offset for 2016-08-14. For the time being, you can use the following workaround:
$ twurl -H ads-api.twitter.com "/1/stats/accounts/18ce53x6d8b?entity=ACCOUNT&start_time=2016-08-14T04:00:00Z&end_time=2016-08-15T03:00:00Z&granularity=HOUR&metric_groups=BILLING,ENGAGEMENT&placement=ALL_ON_TWITTER" | jq .
Here, we use hour granularity. Because clocks turn forward at midnight, the first hour of 2016-08-14 is actually 1:00AM (local). So, we use the 04:00:00Z start time offset. For the end time, we use the 03:00:00Z offset. This correctly returns time_series_length of 23. Then, you can sum the arrays for the particular metrics you’re interested in.
We appreciate you letting us know about this issue. We’ll work on getting this fixed, but do not currently have a timeframe. Apologies for the inconvenience.