Did you sweep private keys or import them? I don't think the option to sweep private keys was there 2 and half years ago.
If you imported them then a restoration from seed would not restore the imported private keys.
@OP, if youre sure the seed is correct and what HCP suggests isn't working. Can you go to wallet>master public key from the top menu and copy and paste the key beginning with "xpub" here.
There isn't anything anyone can get with that key other than information about your wallet that is public to nodes already.
For a 2.5 year old wallet it'll be the old style hexadecimal MPK rather than a bip32 xpub. It's worth a try though. We can create a watch-only wallet and see if there are any transactions.
Ah your wrong about the privacy leak though. The MPK is normally not revealed to electrum servers so exposing it is a big privacy leak. It also has security implications. If any of his private keys were to leak too then his entire wallet could be compromized.I'm not particularly sure any of his public keys would be exposed. However @op if you have a problem with this, you can PM me or the user I just quoted with the public key.
Also, if the seed formats are the same and a new wallet is created then an xpub key should be created shouldn't it? Otherwise, the problem op is facing is merely a compatibility issue.