Hello AndrRoos
Thank you for your PM.
Could you clarify something please.
Do you remember if you have been able to recover your wallet on Tails at least one time before upgrading the Electrum software?
Because as I understand, you've created your wallet and its seed on MS Windows first.
But Electrum is using UTF-8 character encoding, so maybe the character set that has been used to create your seed on MS Windows is not the same as the one used on Tails?
In order to eliminate the dependency on a fixed wordlist, the master private key and the version number are both obtained by hashes of the UTF8 normalized seed phrase.
[...]
Electrum 2.0 derives keys and addresses from a hash of the UTF8 normalized seed phrase with no dependency on a fixed wordlist.
https://electrum.readthedocs.io/en/latest/seedphrase.html