TrueRev communicates with Quickbooks via the Quickbooks API. The Quickbooks API doesn't support all of the functionality that is on the website.
If you manage custom fields in Quickbooks and see a column "CATEGORY" - it means you have a Quickbooks plan that supports extra custom fields like Quickbooks Advanced.
"Customer" custom fields are one thing that isn't supported. TrueRev can't see any of these - even if they are assigned to Invoices.
Follow these rules so TrueRev can see Quickbooks Invoice Custom Fields
"First three" means from the bottom of the list of fields up - the first three:
"Transaction" category fields
"Text and numbers" type
Make sure these "first three" custom fields are:
Made active - Quickbooks API doesn't recognize active/inactive
Are assigned (all checkboxes checked) to all "Sales" entities: Sales Receipt, Invoice, Estimate, Credit Memo, Refund Receipt