IHeartradio has changed their streams and the updated streams are already linked to our databases.
If you have an IHeartradio station saved to a preset or set as an alarm, it will need to be updated.
All you need to do is a fresh search for your station under IHeartradio.
Once it is playing on your radio you will want to over ride your old preset buttons, and update any alarms you have made, as those point to the outdated streams.
If a simple search doesn't fix the issue, a refresh of your radio and router, then a fresh search should take care of it.