Electrum will generate P2SH addresses that start with 3 if you create a multi-sig legacy wallet.
This is true... but OP claimed he had a "segwit" wallet with 3-type addresses that he was attempting to restore... so, I guess the options are:
1. Original wallet was actually a multisig wallet, NOT segwit
2. Original wallet was a 2FA legacy wallet, NOT segwit
3. Wallet was P2SH-Nested SegWit generated from BIP39 (or Electrum SegWit) seed
4. Wallet was P2SH-Nested SegWit generated from Hardware Wallet
If the OP is 100% sure they had a SegWit wallet, then the only real option would be #3... if OP is just thinking "3-type address = SegWit, I had 3-type address, so I must have had SegWit"... then several of those options become a lot more viable!
Were there any older versions of Electrum that allowed you to specify the derivation path when
creating a new seed? (not restoring). If so, would that have allowed a user to specify/set m/49'/0'/0' and generate P2SH-segwit addresses?
I honestly don't recall if that was ever a feature... I don't remember seeing it.