First noticed with self-compiled version, then confirmed with today's master appimage Version 5.1.90-15f7aab. First noticed when looking at a current (December) transaction in Investment account. Right clicked and selected go to brokerage account. Brokerage account ledger displayed only non reconciled transactions. However, it also does so in other checking, savings, cash, and credit card accounts. Seems to be anything other than investment accounts. Unfortunately, I don't have an older appiamge around to test.
I've compiled several different versions, going back about one day at a time, and all exhibit the same behaviour - including versions older than the last on I knew worked correctly. Thus, I no longer think this is a recently induced bug. Indeed, moving my kmymoneyrc out of the way, the ledgers all look OK, so I'm going to have to do a line by line compare (or try changing settings one at a time to see which one is responsible for the misbehavior.
I have not idea how, but "Do not show reconciled transactions" got checked. Stumped me completely until I started going through all kmymoneyrc line by line. Sorry for the noise.