Please provide us the two screenshots. If both are using the interrail rail planner app, have you made sure that both are updated?

That's odd indeed. The best thing to do first is to double check whether you have the latest version of the Rail Planner app. Although please note that our app has been designed to operate offline so the timetables are not updated regularly. The best thing to do is to check the schedule directly on the rail carrier’s website. You can find the Hungarian CD over here and the Polish PKP over here. You can add the journey manually to the travel day if the schedules do not align. You're also welcome to reach out to our customer service team with the journey details so that we can follow up on it. Pro tip for traveling in Poland: if you make a reservation for a domestic Polish trip locally at the station - it's free of charge :D 

Those 2 things are not related. You can have an online application without frequent updates (as we can see on the Interrail website). But you can also have an offline app with frequent updates, as Czech and Slovak railways are showing.