~to sweep the paper wallet (which was holding only a bitcoin(BTC)) with the Electron CASH (BCH) wallet. The Bitcoin (BTC) vanished.
are you sure your "bitcoin" has vanished?
you are using a bitcoin address in a bitcoin cash wallet. that wallet (being Electron Cash) is obviously showing your Bitcoin Cash balance of the imported address which should be zero!
check your address in a block explorer or import it in a bitcoin wallet (like Electrum) and see if the balance is still there or not.