My application follows the server-side authorization flow, as described in https://developers.google.com/youtube/v3/guides/auth/server-side-web-apps . I force prompt=select_account.
In the most basic case, in the "Step 3: Google asks for user consent" section, the user sees a screen with one or more "Select an account" accounts. If the account that the user selects has only one channel associated with it, the flow then goes directly to "Step 4: process the OAuth 2.0 server response."
If the user has many channels associated with the account, the user may see another screen called “Choose your account or brand account”.
For me personally, I have two Google accounts: a personal account and a work account, and I see them on the "Select Account" screen. If I choose my personal account, I will go directly to the application. If I select my work account, I will see an additional screen on which I can choose my “personal” work with the YouTube channel / account or the general channel / company account. In total, I can manage and access 3 YouTube channels / accounts.
The problem is that some users don’t see all of their channels listed in the "Select an account or brand account" section. If users register on YouTube at the same time, they can still access all their channels from the account selector in the upper right corner on YouTube, but they cannot see them at all in the selector. I tried using the YT API channels.listin such cases, but it does not return the missing channels, but only the one that the user selected from the selector.
It seems like I missed something obvious here, but since I don't have much control over the OAuth stream, I'm not sure how to fix it. Is this even a problem at my end, or do I just need to instruct users to do something on their part?
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