Deploy sourcemaps to firebase web hosting with flutter project? - Stack Overflow

I am debugging a complex issue that only occurs in prod. I am trying to upload sourcemaps so that I can see what lines are actually failing, however I can not get firebase deploy to actually deploy my sourcemaps.

Here's my firebase.json:

  {
      "flutter": {
        "platforms": {
          "dart": {
            "lib/firebase_options.dart": {
              "projectId": "XXXXXXXXX",
              "configurations": {
                "web": "XXXXXXXXX"
              }
            }
          }
        }
      },
      "hosting": {
        "source": ".",
        "ignore": [
          "firebase.json",
          "**/.*",
          "**/node_modules/**"
        ],
        "predeploy": ["flutter build web --source-maps --release"],
        "rewrites": [
          {
            "source": "**",
            "destination": "/index.html"
          }
        ],
        "frameworksBackend": {
          "region": "us-central1"
        }
      }
    }

My predeploy works - I can see that the main.dart.js.map gets built, but when I run firebase deploy --debug I can see it never gets uploaded.

How can I actually force my sourcemaps to get uploaded? I have been looking at documentation and I can't find anything about this.