As I'm personally not a regular Showcase user, it's taken me until now to realise Showcase has no Vault integration at all. Given that for years it's been a bundled package in Product Design Suite, and is supposed to fit into the "pie in the sky perfect world workflow between products", it's crazy and it really needs to be Vault enabled.
Please enable full Vault capabilities for Showcase. This would include importing 3D data from Vault to create a scene, and the ability to check in all Showcase scene files and data to Vault.