Hey @James_Carl, my best guess is that it is a guest user trying to modify custom fields. Our premiumness model can admittedly be a bit confusing to reasonable. Here is link to a matrix at the bottom of the custom fields docs that shows access control for custom fields: https://asana.com/developers/documentation/getting-started/custom-fields#access-control
Hopefully that helps clarify things.
Actually the Personal Projects was the culprit. This appears to throw off the account type as the API treats as non-premium in a premium. Our best guess.
I think that Custom Fields doc page you linked to is a bit out of date?
**Note** : Currently Custom Field metadata must be defined in Asana’s user interface before they can be accessed through the API. We will be adding methods to manipulate Custom Field metadata soon.
which isn’t true any more; and also this box is now “Yes”, right?
Hey Phil, thanks for bringing this to our attention. It does need to be updated as the ability to modify custom fields has been added to the API since this was written.