Time Machine on Catalina 10.15.6 only shows local snapshots
After applying the Catalina 10.15.6 update to my MacBook Pro Retina Mid-2015, Time Machine only shows the local snapshots that are stored on the local disk. The backups do get the the remote disk but are not displayed in the Time Machine UI when you enter Time Machine. The only backups that are displayed are the backups that have been taken since 10.15.6 was applied.
The local backups are being stored over a network to a Time Capsule during the "cleanup phase". The sparse bundle on the Time Capsule, when mounted, does show the new backups since 10.15.6 was applied and every other backup back until the Time Capsule was first setup in 2017.
When Time Machine is activated, all of the local snapshots are retrieved from a "hidden" partition of the main disk and mounted under /Volumes and those are the only backups that are available in the UI.
I never had looked into Time Machine until now when it broke. The behavior that I am seeing makes me think that a change was made to Time Machine for10.15.6 that broke the merging of the local snapshots with the list of backups on the remote disk. My guess is that there is a bug in the code that is removing duplicates between the list of local backups and remote list. It is also appears that, in contrary to the document here, https://support.apple.com/en-us/HT204015, local snapshots are now being preserved at all costs, regardless of age, so that Time Machine can be used when the laptop is not attached to the remote disk.
As I said earlier, it is appears that there is a bug when Time Machine is attempting to merge the list of local snapshots with the list of backups on the remote disk and the UI code fails, leaving a list of backups that contains only the local snapshots.
I would classify this behavior as a regressive bug introduced with 10.15.6.
MacBook Pro Retina
