@rvdborgt Any ideas?

If you are already travelling and assuming you have enough travel days on your pass I am confused by your problem.

I thought that as long as you open a travel day and add a train journey, either from the planner or manually, a QR code for that day is generated.  You can simply then add train journeys as you board them up until 23,59. That QR code is the same for the whole day.

If a train is not showing in the planner but is in the operator or station timetable you can always add it manually (checking of course you have a reservation if needed)

1. When exactly does a journey disappear? After saving it to My Trip or after adding it to My Pass?
2. When the app says there is no journey, is the date shown at the top of the screen correct?
3. If the date at the top of the screen is correct, is your journey still visible in My Trip?
4. Have you added a manual journey at some point?
5. What is your app version? See More, scroll to the bottom. If it is lower than 24.2.0 (iPhone) or 24.2.1 (Android), then update.
6. Check the basics to run the app:
https://eurail.zendesk.com/hc/en-001/articles/5545614121757-Basics-to-run-the-app
7. Restart your app and try again (some people reported that this helped for QR codes that won't show).
8. Restart your phone and try again.
9. Do you have an iPhone or Android? Which version of the operating system?
10. If nothing helps, go to More > Settings, scroll to the bottom and enable error logging. That won't solve the problem but will help customer service.
11. Create a support request:
https://eurail.zendesk.com/hc/en-001/requests/new
Give them all details, screenshot(s) and mention that you are currently travelling, so they can prioritise your request correctly.
12. Also send your device ID to customer service:https://eurail.zendesk.com/hc/en-001/articles/4571649483165-Contacting-us-about-an-issue-