Tracking down an errant Job Type

I have one customer dating back 20 years who, in my new to QB days I made a job type Retail. We no longer use job types but every time I create a new job under this customer that Job Type appears. It is inactive in the Job Type List. When I run a report for the transactions using that job type, it comes up with a handful of invoices that the type supposedly links to. The job for each of those invoices has NO job type listed so the invoices shouldn't be linked to it. I've been pulling my hair out to track it down, but cannot.

It's kind of become one of those "I won't let it beat me!" things. If I can unlink that job type from the invoices, I can delete it once and for all.