Specifically, the "General" line items, which appear to be the same as "Total" in all the other statistics categories... are only reporting monthly values on the annual and "max" graphs, rather than the actual cumulative values that they ought to be showing. All the itemized costs/productions appear to be properly showing cumulative values for the time steps selected.

Should probably have mentioned in the original post:

Update 4.1 | v0.8.4 (b587)

Issue persists in v0.8.4a (b588). It also doesn't appear on the changelog, so that's expected.

For future reference, this issue is caused by the fact that some stats are tracked through SUM and some with AVG aggregation functions.