We are planning to travel from Zurich to Vienna on Sunday August 4 on RJX 165 using our Eurail pass but have been unable to book seat reservations by any method (eg OBB says not available, DB says all booked). Have been monitoring this for months and have never been able to make the seat reservations for this particular train.

Eurail says seat reservation for this trip is only recommended, but OBB says travel only guaranteed with reservation on peak travel days (which presumably this will be), and as noted above DB says all seats already fully booked. Based on OBB live it does not appear the train is actually fully booked, and based on everything I've been reading online that also seems unlikely... but we're getting a bit nervous.

Is it possible that we will still be able to make a reservation closer to the date of travel? If not, is there any chance we can get on that train without a reservation - or are we just out of luck?

Also, looking at alternate methods to get there such as via Munich or Innsbruck don't seem to work either; basically it appears we are not able to book seat reservations on anything involving RailJet trains on that date.