I don't think this is new behavior, but it's a different slant on oft-reported problems with calculating net worth. In essence, it's screwy and inconsistent. I traced my problem to one (not-online) brokerage account, but darned if I can figure why there are issues.
In my case (QM 7.2.0), these "reports" agree with my brokerage: SideBar accounts, Accounts Summary (deprecated), account Portfolio, account Dashboard.
These reports do not agree with my brokerage: (Net Worth, Net Worth over Time (deprecated), Net Worth on Home Tab.
No hidden transactions (can we even do that in QM?), no "unusual" transactions around the date the inconsistencies start showing up, no shadow transactions that I can find.
So there seem to be (at least) two different ways that QMac calculates net worth. Anybody else seeing this?