BUG: Git Bash on Windows - can't pass prefix to GCS module?

I’m trying to set the GCS settings for our statefiles for terraform, passing it as a argument on the command line when calling terraform init, however while the backend configuration seems to apply, the prefix is always ignored.

What I run:
terraform init --backend=true -backend-config="bucket=bucket-i-own" -backend-config="prefix=/terraform/script-test/network/" -get=true

What I get in the terraform.state:

    "backend": {
        "type": "gcs",
        "config": {
            "access_token": null,
            "bucket": "bucket-i-own",
            "credentials": null,
            "encryption_key": null,
            "impersonate_service_account": null,
            "impersonate_service_account_delegates": null,
            "prefix": "C:/Users/Username/AppData/Local/Programs/Git/terraform/script-test/network/"
        "hash": 2430640059

Note the prefix is completely wrong, instead seemingly to use the pwd from my git shell?, my colleague runs the exact same command on linux, and gets the right output, with the prefix being parsed correctly.

Is this a windows bug, or am I missing some required formatting for the arguments in windows which doesn’t seem to be currently documented anywhere?