I'm not sure where “Bayeau” is. However, the planner in the app is not too reliable because it doesn’t get enough updates. The operator's own app or website is most reliable for its own trains, so in this case https://www.oui.sncf/

For the mobile pass, you just need to add the train/journey to your trip and then to your pass. That's your ticket.

Reservations are sometimes required, such as for TGV, are separate and don't need to be added to the pass. You don't even have to buy them through the app: you can also buy them at the ticket office or ticket machine (and that's cheaper too).

Thank you.  I think it is a technical issue as it will not allow me to add a journey to my pass on a travel day.  (It defaults to an earlier day and says I must declare it as a travel day).

my option is to buy a sncl ticket  for ter travel which is available but that seems unnecessary if I have a mobile pass for that day, just not barcoded.

There is an option to add trains that are not showed on the Railplanner app with this option yo ushould be able to activate the correct day as Travelday :/

You may ask for help from Customer Support https://eurail.zendesk.com/hc/en-001/requests/new

I did add a journey manually for the second travel day but if will not allow me to add it to the pass.  It defaults to a different day than the one on the manual entry.  
 

Customer service said to ask the community.  I will try again.  I wish there was a number to call. 

I've just tried it myself and it worked correctly for me (3 month continuous pass.) The dates in My Trip and in My Pass ("Show ticket”, below the barcode) are correct (= today's date).

1. What version of the app do you have? 18.1.2 was released yesterday. Please check if there's an update and try again.
2. When does the date change? When you add the manual journey to your trip or only when you add it to your pass?
3. Does the entry in your trip still have the correct date?
4. Do you have a flex pass?
5. If you have a flex pass, try to activate a travel day first and only then add the manual journey. Does that work?

1.  I updated yesterday
2. date is now correct
3. on day 2, it now says “use travel day”. “Last day to use pass”.  I have 3 travel days
4. this is a 3 day in a month pass.
5. how do you activate or cancel a travel day?  The friend I am traveling with has a travel day for September 13.  How do we delete that?  There is no option to delete.

So do I understand correctly from the answer to question 2 that it works now?

Cancelling a travel day is explained here:

https://www.interrail.eu/en/interrail-passes/interrail-mobile-pass/mobile-pass-faq/can-i-switch-or-cancel-a-travel-day

There are a lot of FAQs for the mobile pass here:

https://www.interrail.eu/en/interrail-passes/interrail-mobile-pass/mobile-pass-faq

Thank you.  I am trying to cancel a second travel day in the future that was added by mistake.  I tap on it and nothing happens.  The link does not address deleting  travel days in the future, only the first travel day.

Then you'd better create a new request for customer support and ask how to cancel that travel day:

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

Do mention that you looked at the FAQ about cancelling a travel day and how it doesn't cover your case.