Hi, I had the same problem with a MacBook Pro 2019 starting in mid April that affected Apple Music but I don’t reminder if it affected the Sound Effects (in System Preferences). My only temporary and frustrating solution was to restart the computer. I was given a long “Troubleshooting Procedure that may Fix Problems with macOS El Capitan or Later” in a community forum. I didn’t want to do all that so I tried some simple things like disonnecting an external hard drive and rebooting the sound controller but that didn’t help. At some point I used safe boot and then restarted and it it seems that safe boot may have corrected the problem. Since April 24 I can leave the computer for hours, leave it on overnight, awaken it from sleep, leave the sound paused with Apple Music’s pause button or using the keyboard’s touchpad play/pause key for extended periods of time and I still have sound. I don’t know what actually caused the problem in the first place but that is my non-techie experience and I hope it continues to work because I expect that from a MacBook Pro 2019.