POST /tracks returns 401 with empty body while GET /me returns 200 (Pro Unlimited account)

[antechquity]

Upload via POST /tracks returns 401 with an empty response body ('\n', Content-Type: text/plain, no WWW-Authenticate header). The same access token succeeds on GET /me (200).

Account: jacob-abdo-1 (user id 62867548)
Plan: Pro Unlimited — quota.unlimited_upload_quota: true, upload_seconds_left: null
Client ID: oaKtPwuLDy6dKEUDFwtqhiiPy7Mcwien
App: registered via scripts/sc-api-auth.mjs, redirect URI http://localhost:8080/callback

Auth: OAuth 2.1 authorization_code + PKCE, per the API guide. Token exchange succeeds and refresh works.

Tried, all returning an identical 401 with empty body:

• Authorization: OAuth <token> and Authorization: Bearer <token>
• Freshly refreshed access token
• Refresh requesting scopes non-expiring, upload, * (all return 200, but scope comes back as "")
• Minimal multipart body: track[title], track[sharing], track[asset_data]

Reads work, writes do not.

GET  /me      -> 200  (returns Pro Unlimited plan, unlimited_upload_quota: true)
POST /tracks  -> 401  body: '\n'   content-type: text/plain

This matches the signature in #110, where the resolution was SoundCloud reinstating API credentials server-side. Could you check whether upload permission is enabled for this client / account?