The behaviour of the component ion-item-sliding differs between ionic-v3 and ionic-v4
in version 3, opening a new item closes the one that is currently open, you can check it in the following simulator:
in version 4, a new one can not be opened until the previous one is closed, which requires a double focus on the item, one to close the previous one, and another to open the new one, you can check it in the following simulator: