.asApp() Permissions return 403 Response

Hi, new to using Forge. My app uses UI-Kit and some Confluence REST calls work with the permissions provided, whilst others return a 403 (Forbidden).
If I use .asUser(), the request returns a successful 200 OK Response.

The REST endpoint I am attempting to use is adding a User to a Group:

let bodyData = `{"accountId": "`+userKey+`"}`;
const response = await api.asApp().requestConfluence(route `/rest/api/group/user?name=test-group`, {
                    method: 'POST',
                    headers: {
                        'Content-Type': 'application/json'
                    },
                    body: bodyData
               });

userKey is the Users accountId retrieved using a different API path (which works using .asApp() ).

For Clarification, ‘forge lint’ has been used to edit the manifest permissions, along with deploy and --upgrade installations (Permissions added were required access when the app was redeployed).

Replying to let others know if they are having the same ‘issue’…

Turns out my user Key was set as "value" and not value. This meant that the body Header was being set as:

body: {"accountId": ""value""}

Also as a side note, my initial code block should have used:

let bodyData = `{"accountId": "${userKey}"}`;

The permissions issue was occurring using UI-Kit, however am now using Custom UI and have not faced the same permission error with the contextual methods (asApp/asUser).