verifyCSRFToken fails randomly

Environment: CF2016 + patch17

OS: Windows

Session Enabled and hosted via Elasticache (Redis)

Multi-instance environment

Load: A LOT

Given the two functions:

/**
 * Method used to create a CSRF token, mainly used for login forms - Returns string
 *
 * tokenKey - optional, string. Unique key. Must also be used for decoding the token
 * forceNew - optional, boolean. Defualt to true. Will create new token each time the method is called
 **/
public string function generateCSRFToken( string tokenKey='some-special-key', boolean forceNew=true ){
	return CSRFGenerateToken(  arguments.tokenKey, arguments.forceNew );
}

/**
 * Method used to verify a CSRF token, mainly used for login forms - Returns string
 *
 * token - required, string. The token to be verified
 * tokenkey - optional, string. Defualt to true. Will create new token each time the method is called
 **/
public boolean function verifyCSRFToken( required string token, string tokenKey='some-special-key' ){
	return CSRFVerifyToken( arguments.token, arguments.tokenKey ) ? true : false;
}

The way I understood the CSRFGenerateToken() function, it creates a token and sticks it into the session. Given that our multi-instance environment is using the same Elasticache service (to prevent session duplication) and so the session is shared on all instances, I would assume that the CSRFVerifyToken() would not have an issue verifying the token (presummably that is in the session). For some very ODD reason, it fails for random users - I don't have any debug information other than when the CSRFVerifyToken() function is called, it returns false. 

Thoughts?