Similar problem has been experienced by others on this forum, but I wondered what the resolution was .
We've used 2 days travel on our interrail ticket. Today, on a non-travel day, my wife's (iphone) app has allocated a 3rd travel day. This 3rd travel day has been given the same date day 1 of our travel. Plus, it says that this is also an outbound/inbound day (as is day 1).
So now she doesn't have enough travel days to get home. Plus we she doesn't have the required inbound day available for travel back to the UK.
Contacted customer services but we need resolution in the next 36 hours. Not confident of this getting sorted and convinced we'll have to buy extra tickets.