Difficulty Reserving High Speed Train Seats with Mobile Eurail Pass

For Eurostar: https://www.seat61.com/interrail-and-eurail-passes-on-eurostar.htm

At this point, faced with such abysmal service from the pass issuing company, could you get your money back minus the 15% cancellation fee if you return your pass? There is some small print related to "activation" and I do not know if you fit into that category, but it might well be the easiest option... It won't cost you much more either!

EDIT: I see some 79€ tickets for London-Paris on select departures on 16 May, and 123€ for Paris to La Spezia (for 5 Terre) on 20 May. If you can get your Eurail money back, you really won't lose much at all...

Your experience is unfortunately typical, from recent accounts on these boards...

I'm not sure returning the pass might be a good idea at the moment, since single tickets might cost a bit this close to the trip.

Yes, but being able to obtain tickets at all may be a more important goal at this point.

With the last app update, there are a ton of glitches on the Eurail app. We’ve had ongoing issues with paid reservations dropping off the pass, the same travel day showing twice, etc. Emailing customer service has been useless. Started 3-4 weeks ago and have only gotten the automated response. The Eurail forums are full of people with the same problem, and also no assistance from Eurail. We have gotten all but one travel day on one pass corrected and are in the middle of our trip :-/ TGV ticket guy tonight told me to screen shot the ticket if possible, because he can use that if it later drops off the pass on the app.

Thank you for your help. I followed the directions provided, For Eurostar: https://www.seat61.com/interrail-and-eurail-passes-on-eurostar.htm, and they were perfect. Took the advice about submitting a claim to eurail knowledge bank specifically requesting pass cover number and it worked. They got back to me in 28 hours with the pass cover number. I was able to book my reservations for the high speed trains through SNCB International.

I still have to book a few more trains in Italy but I'm nearly there!

Having looked at the Eurail pass and all the stipulations involved I would never get such a pass. The premise of the pass as popular mythology is that it is cheaper and you can travel all over Europe on it. Just jump on a train. Not so.
Am in Europe now and we are all train transport. It’s easy to book on various apps. Doesn’t seem so expensive, but I am not going to look and compare and take all that endless time to see if the deal of a Eurail pass is better by a few dollars.