It only leaves the Trezor firmware that we haven't checked. You should be at version 1.5.2.
But i would doubt that it is the problem since wallet.trezor.io works.
One thing i don't understand from your responses, is that you said that you were able to create new wallet files following my instructions, up to m'/44'/0'/2'. If that is correct, than your Trezor does communicate with Electrum and your problem should be fixed.

Firmware is updated too.
No, what I meant was, I can create wallets up to any number, but after m'/44'/0'/2 they are all empty. I haven't tried like m'/44'/0'/9 or so, can it be hiding that high?