I also have a similar problem with the backup. Only when my PC is on it can make a programmed backup on an external drive and that is certainly not at night. My agenda warns me 5 minutes in advance that a backup will be made and then I stop Music Playing and the last time I stopped the program Roon. But every time I get the message: Backup failed … / MusicPlaying: Could not start backup because music was playing (or was recently playing). How long must Roon be inactive before the scheduled backup can take place and should only music play be stopped or should Roon be closed? Or is there something else going on?
The programmed backups do work on the external drive of my sonicTransport with Roon Core, which I always leave on and on which a backup is made at night. Moreover, backup works on the external drive of the PC if I give the order for a backup even though there was music playing (it stops during backup).