Hi I'm having the same problem. EOS 1DX MarkII. Sandisk 64GB CFAST. Using Erasing Source Disk (s) After Ingest and Using Unmount Source Disk (s) After Ingest. It does not erase nor unmount. I'm having this issue with two Cfast disks.
Just now I tried a normal CF Card with only Jpeg's shot on them and for some reason this message came up without changing any settings.
For safety, your settings prevent any changes from being saved on your Camera Disk ("/Volumes/EOS_DIGITAL 1/DCIM/100EOS1D"). You can change this in Preferences > Files. For now, any changes you make will not be saved. Open Contact Sheet to view only?
Tried formatting in camera and macbook pro but none of this works.
Any Thoughts?