Some others have reported this but I'm not sure why it happens. You might want to contact 48 support and ask them about it. See the link in my signature below or email them at firstname.lastname@example.org
However, you don't really need the app as you can do everything via a browser anyway.
I am not a 48 employee - if you need to contact 48 support then please click here - if the Chat Now option does not appear on that page then keep trying until it does.