The Place Elevated Slab tool was removed from the Structural task panel in AECOsim Building Designer Ss4. Is the Place Deck tool meant to replace it?
No, the Place Deck tool was not designed as a replacement for the Place Elevated Slab tool. Instead, you can use the new Place Slab tool with the "Place By: Structural Members" method and an appropriate Base Offset value as the relative equivalent. This should provide roughly the same ability but with DataGroup reporting abilities.