Since that year only the 3 baltic states have been included.

Main problems with travel on IR are:

1.the very hard to get and also expensive REServations fpr Hi-Speed and express trains, with Spain and France topping the list

2.IR is not valid on some railways, this varies enormously per country. This is a heritage from the old days when there were just the monopolistic state-railways and since then there have been many privatisations.

3.passing gates, sometimes easy, sometimes very hard to do-no staff in station, noone to help you with this.

Also in east-EUR it often is simply not worthwhile to travel on IR, as local fares (pay as you go) are still quite cheap.

But this does not mean its all worthless-you have to plan and make more information.

You pass is valid in Estonia. However, that has only been the case since last year, so before 2020 I can imagine he had "troubles” with it in Estonia (and Latvia).

If there were problems in other countries, then please specify in which countries and what kind of problems.