The Modeling Import aborts with the following error message: <Modeling object> Failed to be processed. Reason: OPERATION_NOT_ALLOWED: Cannot update system field [custom field]
A custom lookup field with the exact same name exists on both the production and modeling object. Because of this, Align tries to copy the contents of those lookup fields. This is currently not supported.
Rename the custom lookup field on either the Modeling or the Production object.
Align Help Documentation: Territory Modeling