If an employee earns compensation he or she is entitled to it and an employer cannot arbitrarily require an employee to forfeit those wages.
The Court of Appeals reinforced Medex's holding in a severance case, Stevenson v. BB&T. The Court distinguished between severance an employee earns and severance an employer gives the employee for something other than his or her labor (such as in exchange for a covenant not to compete or in exchange for a waiver of claims). Earned severance is subject to the Wage Payment and Collection Law; unearned severance is not subject to the Wage Payment and Collection Law. (Coverage matters because the Wage Payment and Collection Law allows an employee to recover up to triple the amount owed and his or her attorney's fees.)
Is the law any different for vacation pay. I think not. Medex nearly says as much. The Court citing a series of out of state decisions comes to the conclusion:
[A]n employee’s right to compensation vests when the employee
does everything required to earn the wages
If an employer allows employee to accrue or earn vacation based the time they work such vacation "vests."
Note the idea of vesting vacation pay exists in other states, most notably California.