In the electrum console on the offline wallet try to run this command a few times. It will generate a new change address so you'll have the private key in your wallet and be able to sign the transaction:
wallet.accounts[0].create_new_address(1)
To generate new main account addresses (in case those are the ones that are missing) do this:
wallet.accounts[0].create_new_address(0)
The second one actually WORKED for me! This is incredible - THANK YOU. Also, something either needs to be done to auto-incorporate this into the code or make this fix more visible as I am not the only one who's run into this. However, I will bookmark this and spread the word.
Big ups to Bitcoin Pakistan!
EJ