Cache Tolerance in Matlab Pattern Search

I have been experimenting with the following options with patternsearch in MATLAB.

'Cache', 'On'

'CacheTol', tol

'CacheSize', 1e6

From the docs I would expect a very large value of CacheTol simply to cause all the fitness evaluations to return the same result.

https://uk.mathworks.com/help/gads/use-cache.html

However, even with a value of realmax for 'CacheTol' the solver still reaches a reasonable answer.

I am using madspositivebasis2n

Is there an explanation for this behavior?