Active transmitters need high capacity batteries to be able to transmit signals for long periods after deployment. And batteries don’t like heat in general. They will also require fairly complex electronics which again need to be designed to handle the forces involved. It’s not like this hasn’t been done before (eg. GPS guided shells), but it’s just very costly and needs a good amount of physical space.

Instead, most modern cluster munitions (and mines) have mechanisms to disable themselves after a certain period of time. But like you said, nothing is perfect.