Your customer in Quickbooks must only have one email address, and this email address needs to match exactly the email address the customer has listed in Boatyard.
For invoices to sync successfully, your customer in QuickBooks must have only one email address, and it must exactly match the email address listed for the customer in Boatyard. If the customer in QuickBooks has multiple email addresses or their email address in QuickBooks does not match the one in Boatyard, the invoice will fail to send.
QuickBooks cannot process invoices when a category and product share the same name.
Take a look at your invoice line items and compare them to the categories you are using in Quickbooks. Once you've located the category which uses the same name as a line item in your Boatyard invoice, you'll need to change the name of the category in QB.
Update the Category Name:
Go to the Gear Icon → Products and Services.
Click the More dropdown, then select Manage Categories.
Locate the conflicting category and click Edit under the Action column.
Change the category’s name in the Name field to something unique.
Click Save.
Customers not importing
If your customers are not importing from Quickbooks into Boatyard, you want to check and make sure the customer in Quickbooks has only one email address. Multiple email addresses for the customer in Quickbooks will block the customer from being imported successfully.