When importing setting from a GPO into a new GPO which resides in a child domain, the import may fail with validation errors and a message telling that a file cannot be found. The file it is referring to is normally a file inside the SYSVOL share.
When looking at the error message details you notice that the SYSVOL share it refers to is the SYSVOL share of the root domain.
The issue may occur with other workflow functions or when incorporating settings live. If you want to know if you are affected by this issue you should check the SYSVOL path it refers to. Verify if this is the right path referring to the child domain or if it is incorrectly referring to the root domain.
We are planning to resolve the issue in the 5.12 release.
As a workaround, you can export and import the GPO settings using native tools (Group Policy Management Console). Alternatively, unregistering and re-registering the object could work around the issue (with or without version history).