Inconsistent EL on process instance input and output

I have a process that runs every day and it should get the daily data from the beginning of the month to now and put it in a monthly partition in another table.

For that purpose I have set start of my input feed to currentMonth(0,0,0) and the end to today(0,0).

In my ouput feed i have set the instance to both today(0,0) and currentMonth(0,0,0).

In both caseses the output partition was evaluated one month early. E.g. nominalTime: 2016-08-02-00-00, input feed instances: 2016-08-01, 2016-08-02, output partitions: year=2017, month=07