Can't create a copy or import .pez files in Prezi Classic. Essential features

I need to edit a Prezi Classic presentation without affecting the existing presentation which is now live.

Eg. The existing Prezi is relevant for a May release and has been sent to stakeholders to use, and I need to clone it to include the July release without affecting the live May release Prezi.

Please do not tell me you have turned off the ability to “create a copy” or “import” - this is an essential feature. I have always been able to do this.