Not sure if its Roon or the new MacBook Pro? I am experiencing Roon freezing at least every other time I use it? I also so my back up saying its full when the internal SSD had 55% available and I am using the free drop box ?
Are you sure you are not filling up the free Dropbox account. I had to stop using it years ago because the backup size exceeded the free 2 GB storage limit.
Media size is less than 500gb. Not sure of the Roon system size . Should make the Dropbox 2TB ?
I don’t and wouldn’t use Dropbox for the backups even if I had the space. The backup is too slow and restoration would be a multi-day affair. Your best bet, is to backup to the drive in the Mac.