gRPC calls to EOS5 failing

After investigating the community issue https://cta-community.web.cern.ch/t/bad-response-from-nameserver-when-querying-namespace/195/2, we have found a problem when running tools requiring a gRPC call to EOS5. The same problem does not occur when using EOS4.

Here is an example, where cta-admin tf ls is not able to fetch the path from EOS:

cta-admin --json tf ls -v A00760 -l | jq .[0]
{
  "af": {
    "archiveId": "561391",
    "storageClass": "single-copy-backup",
    "creationTime": "1637099602",
    "checksum": [
      {
        "type": "ADLER32",
        "value": "bf1ff879"
      }
    ],
    "size": "1050064779"
  },
  "df": {
    "diskId": "909637",
    "diskInstance": "cta",
    "ownerId": {
      "uid": 48,
      "gid": 48
    },
    "path": "Bad response from nameserver"
  },
  "tf": {
    "vid": "A00760",
    "copyNb": 1,
    "blockId": "0",
    "fSeq": "1"
  }
}

They both have the same protobuf definition:

Submodule path 'common/grpc-proto': checked out '469158af5fed9de6d02e50dd274558c3cbfb2869'

When using EOS5, these dependencies are used for gRPC:

 --> Already installed : eos-grpc-1.41.0-1.el7.x86_64
 --> Already installed : eos-grpc-devel-1.41.0-1.el7.x86_64
 --> Already installed : eos-grpc-plugins-1.41.0-1.el7.x86_64

As for EOS4:

 --> Already installed : grpc-1.19.0-1.el7.x86_64
 --> Already installed : grpc-devel-1.19.0-1.el7.x86_64
 --> Already installed : grpc-plugins-1.19.0-1.el7.x86_64