subscribe2 automatic upgrade loses subscibers

I’m running WP 3.4.1 and tried the upgrading subscribe2 free version 8.4 to the latest free version using the “update now” feature on the plugins page. The update completed ok but the subscibers list was empty – looks as though the upgrade lost the plugin settings, so does that mean that some sort of manual upgrade is required or a “save configuration on upgrade” switch setting somewhere. I’ve searched but can’t find anything about the upgrade process. Is the correct thing to do:

1. Deactivate the plugin.
2. Delete the current plugin directory and replace with the latest version.
3. Reactivate the plugin.

Thanks