Today, I noticed that updating complex split transactions with multiple transfers fails if I try to do something else immediately after clicking the save button. Some updates may take 5 to 10 seconds, perhaps because some accounts have accumulated a large number of transactions. Clicking on a different transaction may silently abort the update.
This bug suggests that the user Quicken user interface is not routinely tested. The best workaround after clicking on the save button is to wait for focus to move to the next transaction. Oddly, some of the elements of the register window near the Save button jiggle while the transaction update creeps through the process. I believe that this problem has been around for a while because I keep finding split transactions that I recall updating, but no effect.
A related bug is failure to save the transaction or notify after leaving the split window. The unsaved transaction warning does not popup if an updated split is not immediately saved. Of course, the unsaved transaction warning is unsettling when the unsaved transaction is no longer visible.