I seem to be having a similar issue described here:
However this is off of a clean install (didn't update the plugin from an older version). The sums show up, but in a sub-site the list just says "No Data". However if I look at the DB table, I can see the entries for the income/expenses I've added.
It does, however, work fine on the main site. Additions appear both in the list and in the sums.
I've also noticed that it seems to be messing up the styling on other WordPress Admin pages. I'm guessing this is due to the styling being queued to the wp-admin without checking to see if it is the finance page. Nothing major on that part asofar, but it shouldn't be happening.