I've started experiencing this today (not sure when it started - I know there was an issue recently with the report_downloader).
We're using 'v201702' too, and suddenly empty reports with no errors on specific dates.
I find it strange as this client's account has data for every other day bar the dates I'm running today, for example they have data for the whole of March but not 6th - this is across all of their adword accounts.
I've been running for April and we don't get any data for the 1st but we do get data for the 2nd onwards.
It is possible the account's dont have data for those days, but I find that very odd.