Intermittent "No signature of method" error for delayBetween()

Getting intermittent

groovy.lang.MissingMethodException: No signature of method: script14693466842611017906635.delayBetween() is applicable for argument types: (java.util.ArrayList, java.math.BigInteger) values: [[2001FF, 2602], 3500]
Possible solutions: delayBetween(java.util.Collection), delayBetween(java.util.Collection, java.lang.Long)

for

delayBetween([
	zwave.basicV1.basicSet(value: 0xFF).format(),
	zwave.switchMultilevelV2.switchMultilevelGet().format()
	],state.delayStatus)

state.delayStatus is always set to 3500

Strange, especially since sometimes it’s fine and sometimes generates the error. Is this a known issue?