When performing a migration from 2.3 to 2.5 with DPA's configured in the cluster it was noticed via the Cluster Management page that one of the DPA's upgraded fine to v3.3.8, another DPA was enrolled from the 2.3 appliances but after a full day, this DPA seems to be "stuck" on version 3.3.3. The cluster status shows it as up/healthy, and sessions have successfully been run through it.
However the cluster status remains at 3.3.3.
After enrol to 2.5 cluster, the DPA upgrade to 3.3.8 has not fully deployed to the DPA.
Open /admin interface - System Settings / Status - Cluster Management.
Select the DPA having issues - Verify Version via Cluster Status Page.
Click the Details Tab - Select the check box next to "Appliance Active" - Change the appliance from Active to Inactive, Save wait a minute then change it back to Active, Save.
Then monitor the cluster status page for the update to run and the version number to change.