Thank you for reaching out.
Could you please share if you’re encountering an error message when attempting to send the batch of customer invoices? Any additional details will help us further check and provide an accurate solution.
In the meantime, let's troubleshoot your QuickBooks Online account by clearing the cache to delete the temporarily stored files and browsing history that might be causing the issue. Also, ensure you're using supported, up-to-date browsers to rule out any browser-related issues.
Please leave us your response, or if you have other questions or concerns.