Thanks for the additional context. It sounds like the behavior may have been a by-product of the major data error you mentioned. Is that accurate? Generally, I see the “Invalid access token ” when making subsequent to get an access token. This is because each time you call to get an access token, it invalidates the previous access token that was issued. To prevent this, you can submit a support request to increase the index tolerance, you will be able to generate tokens at different indexes so the tokens won’t get invalidated. Here is the post with more details on this topic you can check out :
Let me know if this helps.