Do you mean the pass is not visible anymore in the app?

Please check if there are any app updates and then check again.

Thank you. I already did it but the APP is uptodated and the problem is that it says the pass is in another device but the device is exactly the same.

The pass is connected to the phone and only Customer Support can disconnect the pass from your phone. Only then can you connect your pass to the phone again.

You should immediately contact Customer Support through the form below.

Customer Support is overloaded with requests so you need to clearly write that when you will be travelling so that Customer Support can prioritise your request correctly. Please also write your pass number in the request. The pass number is in your confirmation email and in your Interrail/Eurail account.

https://eurail.zendesk.com/hc/en-001/requests/new

The rules state one has to go online at least once/3 days-and it seems you did not do that-forgotten etc. I conclude that may be the explanation that it got disconnected. Seems indeed a case for support

No that can't be the cause: you can only check for updates when you are connected to the internet and at that point, the pass will become active again. It help to read the FAQ to understand how it work.