Client on 2018.8 has an employee that has disappeared - POOF! gone

Client is on 2018.8 and upgraded from prior version in Feb 2019.  One employee shows on the Data Entry Audit Report for being paid in May 2019.  That employee no longer shows anywhere in the PR_Employee.M4T file - at least as far as I can tell.  The only way to verify names, of course, is to create a file using the PIIWrk file, so based on that, the employee is gone.  If the employee is still in one file but not in another, I guess I have no way of telling.

Anyway, I'm ready to freak out right now.  Employee does not show up in Check History file.  Might have been renumbered, but would have also had to have a new name when renumbered, because the name is gone.

WTH?