Workflow imports do not work!

I'm trying to write an import statement in one of my WDL files.
The import is:
import "https://api.firecloud.org/ga4gh/v1/tools/getzlab:CopyNumberQC/versions/2/plain-WDL/descriptor" as CopyNumberQC

When I try to add this new file to the method repository, I get the following error message:

Error: Invalid WDL: Failed to import workflow https://api.firecloud.org/ga4gh/v1/tools/getzlab:CopyNumberQC/versions/2/plain-WDL/descriptor.: Bad import https://api.firecloud.org/ga4gh/v1/tools/getzlab:CopyNumberQC/versions/2/plain-WDL/descriptor: Failed to resolve 'https://api.firecloud.org/ga4gh/v1/tools/getzlab:CopyNumberQC/versions/2/plain-WDL/descriptor' using resolver: 'http importer (no 'relative-to' origin)' (reason 1 of 1): Failed to download https://api.firecloud.org/ga4gh/v1/tools/getzlab:CopyNumberQC/versions/2/plain-WDL/descriptor (reason 1 of 1): { "code": 404, "message": "Methods Repository entity getzlab/CopyNumberQC/2 not found.", "timestamp": 1542237280763 }

Needless to say that the method getzlab/CopyNumberQC/2 exists and I have full permissions to access it.

Does anyone know why this is happening? Is there a different syntax for the import statements?

Thanks in advance!
Ruslana