401 Error with the private_access_tokens endpoint

So, i created a development app store (Checkout UI Extension with the targets purchase.address-autocomplete.suggest and purchase.address-autocomplete.format-suggestion) in the Plus plan to build a custom feature to my on Store, so this app will not be listed in shopify app store. to do what i want, i nedded the permission for protected customer data. so i submit the request, set the distribution to my own store and went to test it. (when i set my store, the field to submit the request for protected customer data disappeared of the page API access requests to)

but when i arrive in checkout my app receive a 401 error with the private_access_token

Expected behavior

no 401 error

Actual behavior

401 error even with the permission granted apparently (i dont know if its granted, because i cant see anymore in API access request pages.

Steps to reproduce the problem

1. create a development app store in Plus plan (Checkout UI Extension with the targets purchase.address-autocomplete.suggest and purchase.address-autocomplete.format-suggestion)
2. try to submit the request for protected customer data
3. use the endpoint with the private-access-token

Debug logs

// Paste any relevant logs here

from shopify support:
"I have completed our initial internal testing and can confirm the issue you described. It appears that even with the Protected Customer Data (Address) permissions active for your custom distribution app, the token is not being issued correctly on the Plus development store.

Current Status & Internal Report
I have formally documented this behavior and submitted a report to our developers for further investigation. Because this involves the complexity of Checkout UI Extensions and private access tokens, the review process can be intricate. At this stage, I don't have an exact timeline for a fix, but please rest assured that it is now on the radar of our engineering team."

The issue does not name any repository files, tests, or entry points; start by tracing the private_access_token endpoint and reproducing the request with a Plus development store and Checkout UI Extension. Done would mean the endpoint issues a usable token without a 401 when protected customer data permission is active, but the report indicates the behavior may require Shopify platform changes.