We have the same exact problem. We've uninstalled and then reinstalled the app, but it still crashes. I've tried with two different accounts and it's the same.
Try restarting the Roku device between the Uninstall and Reinstall procedure.
Correct procedure is Uninstall, System Restart, Reinstall. (Remove, Restart, Reinstall)
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Seems to be working properly on my Ultra 4660 with 11.5 OS.
If the above does not work for you, post back with Roku model number and Software version (Settings/System/About). What stations were you trying to listen to, or did it just crash upon launching the channel/app?