Not all seeds are the same, some of them are of different standards and/or have different derivation path. You have to notify Electrum of the correct seed format and derivation path for your seed to be successfully imported.
Just to check, are you using Electrum 2.9.0? The latest version allows you to state if the seed is created in a Multibit HD wallet.
Did you follow the steps: In the install wizard, select "Standard Wallet>I already have a seed>Key in your seed phrase AND click on option and select BIP39".
Thankyou so much for replying.
To clarify, yes I used Electrum 2.9.0.
Where does this version allow me to state if the seed was created in a Multibit HD Wallet?
I followed their YouTube video instructions step by step:
Standard Wallet>I already have a seed>Key in your seed phrase > Select BIP39 > typed m/0'
I'm not technically minded, but perhaps it didn't work because the original seed was made on the hardware wallet keepkey rather than the software Multibit? Does the hardware wallet require a different BIP or m/0'