OBB doesn't allow seat selection anymore?

I think your problem stems from buying the tickets on DB . I purchased RJX tickets ( Munich to Vienna )about three weeks ago , but bought them on Austrian State Railways . No difficulty buying two seat reservations with the transaction . . OBB is the operator of the train , not DB .. Also , if buying from DB you could have done that with a Bayern ticket - about 45 Euro for two people .Any change in your ticketing would depend on the grade of ticket you purchased

Reservations and tickets are separate. You don't need a ticket to make a reservation. You can buy a ticket from DB and a reservation from ÖBB and vv.

A few more remarks:
- This is a DB train. It only becomes an ÖBB train after Salzburg.
- When you reserve seats for multiple persons the system will try to seat you together. If that is not possible selecting seats on a seat map won't help either.
- Reservations are not compulsory...
- You can't change reservations. You are free to sit somewhere else though.

Don't overthink this. This is mass transit.

Thank you both for replying. I read a lot of information before buying my tickets. I chose first class for a little more comfort and legroom, and could only get sparpreis prices from DB. The train is listed as RJX 67, so should be one of the newer (red) OBB trains?
As I noted, up until today I was able to see the seat maps and pick my seats, but could not reach the check out page. Now there’s no option to view the map and takes me directly to checkout.
I suppose worse things can happen. At least we will have reserved seats…. 😬

" Bayern Ticket would not have been suitable for this journey because they are not valid in RJX trains." Obviously , but you can make that trip easily on regional trains which are covered by Bayern ticket

Could be worse: https://youtube.com/shorts/ec3Nd0wvzME?si=nyV_Uhd3KZenNb46

@James , really good point ;-)

The OBB time frame is 180 days out , sooner than that you have to wait The RJX 69 tickets for my trip ( Munich - Vienna ) were purchased , with reservations , on 4/24/26 for travel on 10/21/26

But I've just tried to buy a ticket from ÖBB more than 180 days out and they won't let me - so what did these people do?

Nothing out of the ordinary. That's their standard advance booking period. The one-year advance booking period applies only to DB, but it has little practical significance.

To confirm the sale date , go into Bahn ( The DB site ) and fill in the information for your trip . When you reach the end and hit search , the potential trains will be listed , and the last column will indicate the pending date sale of the ticket begins . Buy the ticket on OBB

I suppose it's better to have guaranteed seating in case we're slow to board. At least, the OBB website indicates this train falls within the "peak travel" period.
We can always switch seats if better (unreserved options become available). I didn't realize that Salzburg would be the first stop on this train, so that makes it much easier.
Thanks for the track info and timing advice, @me.crewe!

That youtube video confirms that a lot of problems non Europeans encounter with train travel are due to booking to early...