Opportunity record disappears, Opportunity/Estimate #To Be Generated

I have a situation where one particular salesperson seems to somehow be severely corrupting Opportunity and Estimate records on rare occasions.

From what I've learned, the salesperson is creating/saving an opportunity, creating estimates from the opportunity, going along with business as usual, and somewhere during the process the opportunity is radically corrupted to the point that it essentially "disappears" from NetSuite.

Once the Opportunity record is corrupted, it takes the linked Estimates along with it. The Opportunity record no longer shows up in Transactions > Sales > Create Opportunities > List. If we view one of the Estimate records still linked to the corrupted Opportunity, we can see that the Estimate now has a number of "To Be Generated" and the parent Opportunity record is also now "To Be Generated."