The Lightroom backup is placed in a zip file. You need to open the zip file and retrieve the catalog. Have you done that?
Yes I have, attempted to do so from each drive. Get message LR cannot use the catalog because it is not
writeable & cannot be opened
Sent from my iPad
Just in case you haven't considered this, the backup file cannot be opened from within the zip file. You have to remove the catalog from the zip file in order to use it. If you have already done that, then right click on the catalog and choose Properties. Make sure read-only is not checked.
OK that worked. In the past I hay have done that but just forgot what I had done. Thanks.