The guide book is correct. The train station is called Hallstatt but you need the ferry to actually get to the town. My app knows Hallstatt. If yours doesn't, then check for updates.

@gregohb If you use the correct spelling with 2 "t" at the end, then you will find the station.

Actually the Eurail app sees Hallstatt - but does not see any trains. But the OBB app sees probably a dozen. I chose the same day and time for both

On the Eurail app : Vienna to Hallstatt : “Sorry we can’t find any trains that match your search”

OBB app (same day and time) : trains at 10:15 am 10:25, 10:55, 11:15, 11:55, 12:15, 12;55, etc et

The last leg in those journeys are rail replacement buses. It would seem the railway line through Hallstatt is closed in this period..

The rail pass does not work on rail replacement? I thought so 

but even if not it would be helpful to show how to get to Ebensee or wherever 

The pass is valid on rail replacement buses.

The interrail app runs offline based on periodically downloaded timetable data and is not the most accurate source of running information, as you have seen apps and websites of local operators provide better data and it is these you should rely on for correct times.

These links may appear with a subsequent update of the interrail app (check that yours is the latest version on your app store) but if not you can always fall back on adding these journeys as a manual entry.

It looks like the timetable snapshot used for the current version of the rail planner app already included the cancelled trains but not yet their replacement buses.

The same is the case for the DB and CD planners. That probably means ÖBB are/were late in delivering the replacement bus timetables to the European Timetable Centre.

Hello! Thanks for your question :) 
I would recommend double-checking with the railway carrier by visiting their website and checking their timetable.
If a connection is not showing, you can add the journey manually. To add a journey manually, please do the following:

In the timetable section, you may type in some random characters within the "From" field. Because the timetable won't recognize any stations, it will give you the option to add a station manually. Click on this option and you can proceed to enter the journey details manually, and then add it to your pass.
 

Ok thanks. So the app essentially down loads the entire database to your phone - and that’s why it works without internet. How often is app updated? 

Not very often, check your app store, it updates by a complete app update, not an internal update of the timetable data, a very odd way of managing this.

Every few weeks. Serious planners on the other hand update at least twice per week.