This only started happening for me last week but my partner says it has happened with his app before. Attempting to buy tickets with a half fare card in advance is not longer possible. The app displays “Show Offers” which goes to a fail page saying ‘Connection offers failed’ with error code NTTIF-3004. This is really annoying as the dégriffé tickets can’t be purchased. Having to go to a ticket office or machine is not convenient. Before you ask, I logged out, deleted the app and reinstalled. Same issue. The phone is on the latest iOS so no conflict there.
