PieChart panel shoots huge Interval / IntervalMS on 'query'

Any logical explanation why interval is so big in PieChart panel?

{“panelId”:4,“range”:{“from”:“2017-08-21T14:13:09.146Z”,“to”:“2017-09-20T14:13:09.146Z”,“raw”:{“from”:“now-30d”,“to”:“now”}},“rangeRaw”:{“from”:“now-30d”,“to”:“now”},“interval”:“7d”,“intervalMs”:604800000,“targets”:

because it only wants a single data point back. (I would guess)