Riding a horse in game causes the game to stop responding to the player’s actions, (Torches can be placed but only the flame texture will show, blocks can’t be broken, etc.) and forces the player to quit the app for it to return to normal. When the player closes and reopens the app, the horse being ridden despawns. This has happened to me three times, two of which in this update (1.14.30). Both of the horses that I was riding were wearing armor (diamond and iron, respectively) and one of them had an attached nametag, meaning it shouldn’t despawn. However, both despawned and I have not recovered either.