Failure to download cohort memberships in online mode

While in online mode, the app fails to re-download cohort data for a cohort that was previously downloaded and the data deleted upon logout. This is because the app stores the last sync timestamp and uses that timestamp subsequently when the user attempts to redownload the cohort.

As a user, it is expected that the app downloads cohort membership and associated data (obs, encounters, relationships, etc) upon attempting to download a cohort that was previously downloaded and deleted.