Unexpected focus and editing behaviour in QTableView

AllEditTriggers is set for a QTableView. When editing an element inside it, changing the focus to another widget and then trying to edit the same element again, it takes roughly a second until editing is possible. When clicking on an empty area inside the same QTableView and then trying to edit the same element again, editing is only possible by double clicking or first editing another element. A minimal example for this behaviour is included below.

In one of our applications we subclassed QAbstractItemModel to interact with parameters in a real time process. In this class the first behaviour I described already leads to editing only being possible by double clicking or first editing another element. Since the user has to enter the values via  a (resistive) touchscreen, this can lead to very irritating behaviour.