Error code 1001 when Get sub account details

I got response as " Error code 1001, the user does not exist or does not belong to the current account " when i make API call with Get sub account details .Although It existed as a sub account under master account , I can’t get response ,only get the above error response.
Can i know why I got response for this account?

After few days, i tested again to get account information for Account A by using API , then I can get account information successfully.
API endpoint =>{accountID}
There are other accounts that have similar issue as Account A.
Why there is 404 Error / Error code 1001 occurs sometimes and then information can get successfully again for these account ? Is there any reason for this issue ?

Hi thanks for bringing this to our attention! If this happens again, can you please submit a support ticket with the full API call/response details so we can check this error on our back end and see why it is happening despite the account existing?

Hi , are you using an access token owned by a specific user? Or are you using a JWT token for the account (API key and secret)? As Gianni suggests, a support ticket may help identify a connection between those accounts or something particular about the user permissions of the access token.