Hi @David Heinz ,
To narrow down the problem, we may need more information.
According to your description, the package that has been removed may be the Configuration Manager Client Piloting package. This package is used to pre-upgrade test clients during site upgrade, the source files are located Program Files\Microsoft Configuration Manager\StagingClient. Besides, how was this package removed? I tried remove it manually, but the package cannot be removed.
The following screenshots for your reference:
Note: I am using domain admin, but this package still cannot be removed.
For more details about Configuration Manager Client Piloting package please refer to this link:
SCCM Pre-Production Client Deployment (systemcenterdudes.com)
Note: Microsoft provides third-party contact information to help you understand the problem. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.
If I misunderstand something, please let me know. Looking forward to your reply!
Best regards,
Cherry