“Seat reservation has to be done at the station” is the generic message when Rail Europe can’t sell the reservation. At least it’s less bad than saying “Interrail not valid”.

Rail Europe should sell that specific train though. Otherwise you can use that hidden DB page https://int.bahn.de/en/buchung/start?KL=2&ET=PASSZUSCHLAG

Thanks thibcabe. 

My point is that Raileurope says it can’t sell the reservation for the train in one query and then says it can in the next query - for the same train.

That’s definitely a bug - it makes no sense.

Unfortunately, I don’t know who you could report it to, and I don’t think Rail Europe will be that interested.

Thanks ralderton.

That’s what I thought.

So it’s useful to have a backup plan like the DB site that thibcabe mentioned. 

I'd say report it to Rail Europe, with screenshots of both cases:

https://www.raileurope.com/en/contact/new

They seem to be actively developing their platform, so may be interested in problems. In any case, if you don't report, you can be sure nothing will happen.

I sent the details to Raileurope and a surprisingly fast response acknowledged the bug and said it would be investigated.

….It appears this may be a technical glitch. Our technical team has been notified and will work on resolving this as soon as possible……..

Good to know. I’ll try to be less cynical in the future!