"primary" type on listing of accounts

We have been filtering our data when returnign all of the active/tradeable accounts based on :

  1. type = wallet
  2. primary = true
  3. does not have “staked” in its name (the only way to tell!)

The issue is point 2. Up to now, we have found all of our accounts are set as primary=true until recently when one arbitrary account (UNI) is now returning primary=false

There is no obvious reason we can find and is only happening on a particular account.
There is nothing in Wallet API: Accounts | Coinbase Cloud that explains the merits of the attributes on the accounts.

How should we handle handle this ‘primary’ atrribute as it cannot see why some accounts are not returnign false on this.