Electrum doesn’t support BIP39 (by default) as far as i know, so you will need to use another wallet.
You could try and use an older version of Electrum, then enable BIP39 seeds, and see if that works.
See https://onedrive.live.com/view.aspx?resid=584F122BA17116EE!313&app=Excel for wallets that DO support BIP39 seeds.
But then again, you said you tried Mycelium aswell, which might use BIP44 by default..?
Or, you choose for a “New” wallet when first booting up Mycelium, instead of the “Recovering” option.
You need to click the recovering/restore from backup option and fill in your seed, otherwise it won’t work. Don’t ask me why.
If you currently installed mycelium, you should delete all of it’s apdate and reinstall it.
Possible duplicate of https://bitcoin.stackexchange.com/a/53461/61384
