I see a lot of people have been posting about opening balances changing. This happened to me as well. It seems to have happened randomly to a fair number of my most important accounts.
Using R48.9 Build 27.1.48.9 but started happening a couple of updates ago.
Not sure if related but also happened around time I started having a lot of problems with downloads. Had to reset or re-establish online connections for most of my accounts.