vscode problemMatcher doesn't not recognize Tasking compiler warnings

The following Tasks.json Problem matcher regular expression should match the following typical warning. But it doesn't. ctc W505: ["somedirectory/somefile.c" 350/18] implicit declaration blah blah blah

What is the issue ? I verified the built-in parser matches gcc output errors and warnings.

Thanks,

Satish K

"tasks": [
        {
            "label": "build.bat",
            "type": "shell",
            "command": "build.bat",
            "problemMatcher": {
                "owner": "cpptools",
                "fileLocation": [
                    "relative",
                    "${env:PWD}"
                ],
                "pattern": {
                    "regexp": "^ctc W(\\d+): \\[\\\"(.*)\\\" (\\d+)\\\/(\\d+)\\] (.*)$",
                    "file": 2,
                    "line": 3,
                    "column": 4,
                    "message": 5
                }
            },
            "group": {
                "kind": "build",
                "isDefault": true
            }
        }
    ]

This works for me in regex101.com (ECMAScript(JavaScript)):

^ctc\s+(W|E)(\d+): \["(.*)" (\d+)\/(\d+)\] (.*)

And this in VS Code:

"problemMatcher": {
            "owner": "TASKING",
            "fileLocation": ["relative", "${workspaceFolder}"],
            "pattern": {
                "regexp": "^ctc\\s+(W|E)(\\d+): \\[\"(.*)\" (\\d+)\/(\\d+)\\] (.*)",
                "severity": 1,
                "code": 2,
                "file": 3,
                "line": 4,
                "column": 5,
                "message": 6
            }
        }