The update variable in your code is equal to 1 and is entered as the 2nd input to the clusterer but it doesn't fulfill the requirements for the 2nd input.
The 2nd input specifies ambiguity limits which should either be a real-valued 1-by-2 vector or real-valued 2-by-2 matrix. For more info, see the link.
The 2nd input specifies the automatic update of epsilon where update is a logical value (true|false). In your case, update is 1, not true. To enable this syntax, set the EpsilonSource property to 'Auto', optionally set the MaxNumPoints property, and also optionally set the EpsilonHistoryLength property.
