Google Assistant keeps forgetting my default music provider:
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Thanks for reaching out and I'm sorry to hear about that. Let's sort this out.
Quick question: what Google Assistant device are you using, is it a Google Home device or the Google Assistant button on your Chromecast Voice Remote? In the meantime, could you please unlink and relink your Apple Music in the Google Home app and try again? Rebooting your Chromecast with Google TV and your Google Assistant device might also help.