Issue Description In a recent engagement with support you had your Leads restored, or you plan on restoring your Lead Record. Lead records that are restored will not be able to sync backup with Dynamics.
Issue Resolution If the instance is using Microsoft Dynamics sync then the restored lead will not be able to link between Microsoft Dynamics and Marketo. The lead will exist in Marketo (in the backend, it will keep the MS Dynamics GUID) but it will NOT sync data between the systems. If the lead is synced down from Microsoft Dynamics then it will create a duplicate lead which cannot be merged.