When I went back to ÖBB and enter seat reservation only for the 144 train it said “ticket not available”.
Any ideas?
December 15th is the very first day of the new train time table for 2025. There is a yellow banner on the ticket purchasing page, saying that the negotiations and adjustments for the new time table are not finished yet.
EC trains have different car and seat numbering compared to RailJet trains. This EC train is operated by the Hungarian Railways (MÁV), RailJet trains usually by the Austrian Railways (OeBB).
As the Hungarian website does not offer seat reservations as well (https://jegy.mav.hu/), I assume that the car configuration of this train is not known yet.
Just try from time to time to get your seat reservations. You can do it as well at a ticket counter after you will have been arrived in Budapest.