Purpose, Cause, Effect

In part IV of the Introduction to the Critique of Judgment, Kant defines 'purpose' as a "concept of an object", whereas in #10, he presents it as an "object of a concept", with, in each case, Concept classified as a Cause of an Effect.  So, the #10 formulation avoids the previously discussed problems, entailed by the part IV formulation, of construing a Purpose as a Cause.  However, the alternative, that a Purpose is an Effect, poses a different challenge to Kant's system.  For a Purpose, like an End, as an effect, is without any subsequent effects, a possibility which seems to disrupt the posited, in the 1st Critique, infinitude of Time, without the benefit of the exemption from that infinitude, enjoyed by supersensible causes, as established in the Transcendental Dialectic. That exemption is not available to Purposes, since they entail the possibility of sensible causes having supersensible effects, which unlike its inverse, is not admitted by even Practical Reason.  So, given that, in Kant's system, a 'Cause' necessarily precedes its 'Effect', a Purpose seems classifiable neither as a 'Cause' nor as an 'Effect'.