I have tried exporting keys (from Electrum to Electron Cash) as CSV and JSON but I cannot get either to work (again the 'next' button is greyed out).
Thanks!
There is no need to save anything. You should see a list of addresses. The private keys should be at the right side after 'p2wpkh:' or something similar. There is one more problem. Bitcoin Cash does not support SegWit. You have attempted to sent your coins to a nested SegWit address which means, as far as I remember, that you won't be able to recover those coins without the help of a miner.