Consider me a detective on the case of that missing number, @mike39.
All Invoice transactions must have a number assigned, whether it's manually entered or assigned by QuickBooks' automatic sequence. To search for a specific number in the sequence, head to the Sales tab > Invoices section > and click Invoice column header to sort by those numbers.
If you've noticed that one transaction is out of order or has the wrong number, you do have the ability to alter this sequence. The steps below will help you accomplish this:
Setting up Custom Transaction Numbers
Begin by enabling the setting from the Gear icon (⚙) > Account and Settings > Sales tab > Sales Form Content section > set Custom Transaction Numbers to On > click Save and then Done.
Click the Plus (+) icon and select Invoice. Assign the first number of your new sequence in the Invoice no. field.
Select Save and close. Beginning with your next Invoice, the counter will start on the immediately following number. For example, if you had entered ABC-1, the next entry will be numbered ABC-2 automatically.
This information is also available from our guide on custom transaction numbers for your benefit. I'm attaching a video below in which I set up a custom sequence for a Journal Entry:
With these instructions, you'll have total control over the sequence numbers for all of your transactions. Please let me know if there's anything else I can do to help you succeed with QuickBooks. Thanks for bringing us your question and have a safe and relaxing weekend ahead.