All of my vendors who are 1099 eligible are not showing up 1099 Print List!!!
Have you checked to make sure ALL the correct expense accounts used for these contractors are mapped and selected on the 1099 setup screen? It's possible you don't realize they have bills or expenses hitting the incorrect expense accounts OR you forgot to checkmark ALL the used expense accounts on the mapping step.
The most common reasons contractors are not showing up are:
1. Date for a transaction is not for the correct tax year
2. Transactions are hitting incorrect expense accounts
3. On the 1099 mapping screen you haven't selected ALL the expense accounts used on the transactions. (you can select multiple accounts for QuickBooks Online to look at)