"If the employee quits employment, they must receive their final wages within 7 days or by the next regular pay day, whichever is earlier. If the employee is discharged, they must receive their final wages within 3 days (Nevada Revised Statutes 680.020-NRS 608.040)."

So if you quit, they have until the next payday. It is possible the 26th check was already processed (or in process) by the 19th, especially since it was missing 2 days. The question is more when is the cutoff day for the payroll cycle? Depending on the "holdback"/processing time it is very likely that your last paycheck would be this next one rather than the one on the 26th.

So one could argue over the definition of "next regular payday" in the NV statute, but if their dates are as you state, you will get your $s in the next cycle (which they have already confirmed)