Secure Mail fails to sync intermittently. 

Review App Assignments: Check the app assignments for each user. Ensure that no app is designated as both Required and Optional for the same user. Each app must have a clear, single designation to avoid conflicts.

Examine Group Memberships: Analyze the group memberships of users who are facing syncing issues. Make sure that there are no overlapping deployments of the same app under different categories (Required vs. Optional) across different groups.

Adjust Policies Accordingly: If any overlaps are identified, adjust the policies to eliminate these conflicts. Redefine app deployments to be either strictly Required or Optional, but not both, depending on the user’s necessity.

Problem Cause

The issue is often caused by overlapping app policies within Endpoint Management. Specifically, an application should not be assigned as both Required and Optional for the same user. Additionally, overlapping group memberships can contribute to this problem, as the same app should not be deployed multiple times to a user under different requirements.