Quote from: RepairmanJack on April 23, 2016, 08:29:33 PM

I got to the same place with a trezor Sad

I think the problem is here. It even says "FIXME..."
https://github.com/spesmilo/electrum/blob/master/plugins/trezor/plugin.py

Code:

def get_input_tx(self, tx_hash):
# First look up an input transaction in the wallet where it
# will likely be. If co-signing a transaction it may not have
# all the input txs, in which case we ask the network.
tx = self.transactions.get(tx_hash)
if not tx:
request = ('blockchain.transaction.get', [tx_hash])
[b]# FIXME: what if offline?[/b]
tx = Transaction(self.network.synchronous_get(request))
return tx

def sign_transaction(self, tx, password):
if tx.is_complete():
return
# previous transactions used as inputs
prev_tx = {}
# path of the xpubs that are involved
xpub_path = {}
for txin in tx.inputs():
tx_hash = txin['prevout_hash']
prev_tx[tx_hash] = self.get_input_tx(tx_hash)
for x_pubkey in txin['x_pubkeys']:
if not is_extended_pubkey(x_pubkey):
continue
xpub = x_to_xpub(x_pubkey)
for k, v in self.master_public_keys.items():
if v == xpub:
acc_id = re.match("x/(\d+)'", k).group(1)
xpub_path[xpub] = self.account_derivation(acc_id)

self.plugin.sign_transaction(self, tx, prev_tx, xpub_path)

See how it has to check for transactions before it will sign?

I was finally able to sign a transaction completely offline, but only by painstakingly copying the transaction history from the online watch-only electrum wallet of the same xpub, then copying it into the wallet of the offline electrum.