The releasable latch on the stirrup bar is called a ‘safety latch’. It is designed to flip up, which keeps your leathers on the bar, or down, which allows them to be removed. However, many people use the latch in the wrong position to be safe.
For riding, the safety latch should be down. Always. I know, somewhere you read that they should be in the closed position to keep your leathers in place, that they will release if you fall and your foot is caught in the stirrup.
I’d rather not take the chance that the catch doesn’t release. On my saddle, the mechanism is working well. It easily moves between the closed and open positions. However, I’d rather risk losing a stirrup
off my saddle than being dragged.
Over time the mechanism can freeze up if its not regularly cleaned and oiled. I don’t know about you, but I can’t remember the last time I oiled the latch on any of my saddles. In fact, my Wintec saddle doesn’t even have a latch — the bars are curved enough to keep the leathers on, but allow the leathers to come off pretty easily.