Hi, I'm playing with a 2 of 3 multisig, trying to get familiar with the technology. What I did was:
1) Initialize 3 different ledgers, as legacy. Copy the master public key seen with Wallet->Information for each of them, with the form xpub...
2) Create a 2 of 3 multisig wallet with Electrum. When asked, I entered the 3 public master keys for each cosigner. It looks fine, a watch-only wallet. In wallet->Information I can see the Master Public Keys entered, in keystore1, keystore2, keystore3. Nothing suspicious.
3) I sent a tiny amount of BTC to the first of the addresses shown in the multisig wallet. Received with no fuss.
So far so good, here is where my problems start. I just wanted to spend that UTXO. I go to send, choose an address to pay to, a transaction is generated. I choose to Pay it, set the target fee, finalize it. Now I want to export it to be signed by the wallets assigned to each ledger. There are several export options: Copy to keyboard, to QR code, etc. I think at this point I tried them all, for instance I can 'copy to clipboard'. Then, in another instance of Electrum open the wallet for the first ledger cosigner, then Tools->Load Transaction->From text, and copy there the content of the clipboard. The transaction is shown perfectly fine, amounts, outputs and all, but the 'Sign' button is grey. And on the top left there is a text saying 'Transaction Unrelated to your Wallet'.
Why is it unrelated, if the public master key is one of the 3 in the 2-of-3 multisig? Why can't I sign? I must be doing something wrong...
Any help, please?