Hello Sifepoaz15
Welcome to the SBB Community.
The Swiss Travel Pass is fine for any train. It allows travel at will, no matter which train.
What departure time does the seat reservation read? You can find all trains schedules here: www.sbb.ch/en.
Our support here is limited as the seat reservations are handled by the train operators, in your case by Zentralbahn.
Perhaps you can share a screenshot with your reservation, but make sure you are hiding any personal information such as ticket number or passenger name.
Kind regards,
Roland