seed mnemonic is indeed 25 words for 2FA wallets.
So you have the 25 word seed and you selected the correct type of wallet when attempting to restore the wallet (as show in the image
here)? If your answer is yes to both questions then the possibilities are as follows:
1) the words are mispelt or the wrong words
2) the order of the words is incorrect
3) there is a bug in electrum.
Let's rule out 1 and 2 before we go blaming electrum, OK? If you go to this URL below you will find the entire electrum english language dictionary. All the words that electrum uses to represent seeds are listed there. See if all the words in
your seed are listed there and the spelling is correct:
https://github.com/spesmilo/electrum/blob/master/lib/wordlist/english.txtIf you find all 25 words of your seed there then it's down to the order of the words. If all 25 words are not found there then see if you can figure out what the mistake is i.e. mispelling or typo or what.