Forensic Tools doesn't appear to be sending work to any Distributed Processing Engines (DPE's).
Confirm that the following have been configured properly.
- Make sure .NET 4.7.2 is installed on the DPM and all DPEs.
- Ports 34096 (to the DPM) and 34097 (to the DPEs) are open as needed.
- A mirrored, domain service account is being used to run the DPE service.
- All the involved machines are running the same version of the Processing Engine, and that it's the correct version for the version of Forensic Tools being used.
- Service account has local admin privileges on all the involved machines.
- Case and Evidence folders are shared out, and that the service account has full access to those shares.
- If using MS-SQL, make sure the service account is added to the Logins with the "sysadmin" role.
- On the machine running Forensic Tools, make sure you're logged into Windows under the service account.
- Distributed Processing Engine machines are added under Tools > "Processing Engine Config" in FTK/Lab/Enterprise.
- Make sure your Case folder and Evidence are using UNC paths, not mapped drive letters.
Additional Note: Consider reviewing this help article regarding DPE configuration.