Hiya, first time eurail user here.
I reserved two seats from Paris to Lyon. The tickets showed a cart number and a seat number. However when we got on the train (which was very rushed as it was late and there was no staff to help) there was no cart number which matched the ticket. We hopped on one of the carts and tried to at least walk through and find our seat number but our seat didn’t exist (we were seats 113 and 114 and the numbers on the train went straight from 112 to 115.
We ended up just sitting on the floor of the stairs. Any idea how this happened?? As I was under the impression buying a seat reservation guaranteed you a seat on the train.