How? Can you please give the full instruction ?
Imho this may not work at all, since (at least in the case of Bitcoin) the Electrum seed is not matching the standard BIP39 seed; I'd guess that this could be the the reason for "bad recovery phrase" error.
However, for IanColeman's (offline, safe copy, remember?), in theory you should:
1. Enter the 12 words in the mnemonic box
2. Select DASH in the coin combo
3. Maybe play with the tab from under Derivation Path (you may have to get to one or another set of addresses)
4. Import the private keys to an actual wallet.
I think that a better approach would be to find an Electrum that actually starts and you can recover your wallet from seed (I think that it doesn't matter it cannot connect to any server), see the Addresses tab and get for the top addresses (how many? depends on how much you've used the wallet) the private keys, import those into another wallet.
See web archive page @nc50lc has posted.
Again, your Electrum seed may not work in another software.
LE: if you are OK with Linux, this fork/copy may also be of help:
https://github.com/dashhive/electrum-dash