Hi
this is a bug in non-english settings i need to fix – thanks for reminding me
in the meantime, you can work around this by either – temporarily – switching the admin to english and enter the dates then , or simply type the dates in english if your language would change the month
i.e in spanish it would be 17-Ene-2017 for the 17th of January, just enter it as 17-Jan-2017 and it should work (for some months you might not have to change anything if your language has the same 3 letter abbreviation for a month)