You may experience an issue where you configure a mail or public folder collection to resynchronize, but these settings are not taking effect and the resync does not take place.
This may occur if you perform the following steps with the agents stopped:
1. Configure the collection to resynchornize
2. Commit changes
3. Reapply agent configuration
This happens because the "reapply agent configuration" re-writes the agent's entire config.mdb file, which clears the resynchronization flags set by the commit in step 2.
Do not perform a "reapply agent configuration" after configuring a resynchronization.