I'm having the same problem with weak or no fm radio signal some times. The app radio is installed in a 2010 Nissan frontier.
I emailed pioneer and this is what they had to say.
Good Day,
We do not have any reported issues with the reception on the App Radio, if
possible try connecting a different antenna, alternatively
Please take your unit with a valid bill of sale from a Canadian authorized
dealer to any service center below for evaluation.
Could the gps antenna interfere with the fm antenna?