You didn't check, did you? Actually, 'Mycelium' doesn't work. It give the xprv of receiving (external) adresses, and Electrum expects more "general" xprv, to generate both receiving and change (internal) addresses. You need to use "BIP32" and give the m/44'/0'/0' (instead of m/44'/0'/0'/0 used in Mycelium tab) derivation path. It works with first Mycelium HD Account. I didn't check, but next should be like m/44'/0'/1', m/44'/0'/2' and so on.