There are trains run by Italo on that route which are not valid with the pass, chose a Frecciarossa service and it will be €13 on RailEurope.

Hi @Al_G , thanks for your answer, but there seem to be no Frecciarossa train? See also screenshot below. Is there something I can do to see the Frecciarossa trains as one of the choices? In the main screen there seems no options to choose a specific service.

All right, I changed the destination Florence S.M.N. which I chose first to Florence (any station) in the main screen and now the €13 shows up:

But than I see the rail pass is not valid on that ride? I'm a bit confused . 

Frecciarossa are included in the Interrail/Eurail Global Pass and One Country Italy. 

Hi @Angelo, thanks for your reply. I will ignore the warning.

That fare is for Business Class, only available for 1st class pass holders.

It appears there is low availability in 2nd class tomorrow.

The 09.47 is showing as available in 2nd class.

Hi @Al_G, I just booked the wrong ticket then . I got a ticket for the train departing at 11:12, as it wasn't clear it was a first class ticket. Is there any chance I can fix it? Going to the service centre at the train station?

@Bart1997 is it possible to cancel the reservation? Should be shown in the cancellation policy.

I tried to change the class trough the online customer service, but they couldn't change it. So I had to go to the main station to get it sorted out. Eventually they cancelled my ticket over there and I booked a new one for the right class! I'm now almost in Florence, so it's all good in the end :)