Preferences contains a section to enable/disable shell extensions.
I don't know if it's by design, an oversight, or something that can't be helped, but the settings made in here seem to not be part of a config backup.
Those (and a handful of other settings) are part of the computer config rather than the user config, which isn't currently included in backups.
(Part of the logic is that the extensions won't be the same ones or same versions on different machines, so it might not make sense to carry over blocks to new/different PCs.)
We might add an option to include them in config backups in the future.
