Incremental User Synchronization broken on data center

Summary

1. User Directory Incremental Synchronization does not run correctly on the 2nd Node when incremental synchronization enabled for 1 minute interval
2. It runs correctly on the 1st Node every minute

Environment

1. JIRA Data Centre with at least 2 nodes ( Node 1 & Node 2 )
2. Crowd

Steps to Reproduce

1. Setup JIRA Data Centre with 2 nodes ( Node 1 & Node 2 )
2. Add Crowd directory to Node 1 ( with incremental sync enabled for 1 minute interval ) and wait for it to appear on Node 2
3. Wait for the incremental sync to occur on both nodes

Actual Results

1. Node 1 is working as expected
2. Incremental sync for Node 2 will be delayed or not updated
3. Incremental sync for Node 2 stops working after a while

Expected Results

Incremental sync should run as expected on both nodes.

Notes

User data will be up to date and not affected.

Workaround

Set the synchronization to a one hour interval instead of every minute.