Catalina - Files can't be deleted from Time Machine backup
Hello,
After upgrading to Catalina I made a 1.72TB Time Machine backup (ext. USB 3.0 HD). A few days later Time Machine had added some additional backups. Then I found some large files (video footage) which I don't need anymore, so I deleted them from my Mac, and I tried to delete them from the backup too using "Delete all backups of..." (Time Machine context menu). I could delete the files from the latest backup, but I thought it should have been deleted completely, however there are early backups where the files are still there. When I select one of these files and right click to get the context menu "Delete all backups of..." is not available (missing). This means these files can't be deleted. I hadn't seen such a behavior of Time Machine ever before (since OS X Leopard). Can this be fixed?
Thank you.
iMac 27", macOS 10.12