Yea, 2.6 was released a couple months ago. By the splash screen do you mean the screen with dimmed edges and a FlightAware logo in the middle?
Just to be clear, you never see the login screen or enter your credentials, but it tells you there is an error logging in, correct? Can you provide a screenshot of the error so we can see what’s behind it?
Unfortunately we can’t reproduce the issue from their descriptions nor will Apple let us interact with them.
I have the same problem. I am using an iphone 4 and just downloaded the app. When I type in username and password its says…“Could not log in, check username and password and try again.”