Corrupted Office installation media or a partial download of the Proplus.ww folder. Fix: Re-download the Office ISO or setup files from the official Microsoft Volume Licensing Service Center (VLSC) or your Microsoft 365 portal.
By default, OSE terminates after installation. However, if it remains active, stop the Office Source Engine service (if listed as a service) via services.msc and set to Manual. Proplus.ww Ose.exe