API client returns 403 "insufficient_permissions" on all endpoints after Google account migration

[WristbandStudio]

After migrating my Fitbit developer account to a Google account, my registered
Web API application receives HTTP 403 "insufficient_permissions" on ALL API
endpoints. The token exchange (OAuth2 Authorization Code Grant with PKCE)
succeeds and returns a valid access token, but every subsequent API call fails
with:

{
"errorType": "insufficient_permissions",
"message": "API client is not authorized by Fitbit to access the resource
requested."
}

This affects every endpoint I've tested, including:
- GET /1/user/-/devices.json
- GET /1/user/-/activities/date/{date}.json
- GET /1.2/user/-/sleep/date/{date}.json
- GET /1/user/-/activities/heart/date/{date}/1d.json

Details:
- Application type: Client (also tested with Server — same result)
- Default access type: Read-Only
- OAuth2 flow: Authorization Code Grant with PKCE
- The access token is valid (JWT decodes correctly with expected scopes)
- Tested via curl with the Bearer token — same 403 result
- The app was working prior to the Fitbit-to-Google account migration
- Developer account has been successfully migrated to Google

I also confirmed this using the OAuth2 Tutorial page on dev.fitbit.com —
Step 4 (token exchange) succeeds, but using the resulting token for any API
call returns 403.

It appears the application's API access permissions were not properly
transferred during the Google account migration. Could you please investigate
and restore API access for my application?

Thank you.

[DorisFitbit]

Hi @WristbandStudio 

Welcome to the community. 

To help you check if the ownership transfer was successful, we’ll need some additional information. To keep your details private, I’ll send you an email shortly to move this request into our issue tracker for further investigation. 

[DorisFitbit]

Hi @WristbandStudio 

I've created a customer ticket through issue trakcer. Can you please check your email?

Thanks!