Hello, after installing Android 9 on my Mi A2 Lite I can't access the music on my SD. I Couldn't find other topics, hope to find a solution, thanks in advance!
I would wager that it has to do with the additional security settings in Pie. What music app are you using? Try uninstalling that app, then reinstalling. It should then ask you to approve the required security to access your SD Card. If it does not, then reach out to the app developer and open a bug ticket.