Hello there, @lessenberry-anim.
Let me share some information on how the custom field works in QuickBooks.
When setting up a drop-down list custom field, you can add up to 100 options or items. Once you used-up all the available drop-downs, the Add item link will no longer be clickable.
You can read through this article for more detailed information: Create and edit custom fields in QuickBooks Online Advanced.
Also, I've added these articles to help you manage your custom fields:
- Filter, search, and sort with custom fields
- Use custom fields in reports in QuickBooks Online Advanced
Swing by here if you have other questions. I'm always here to help.