Now after sending funds to the P2SHAddress, I tried to import the private key in Eletrum and it was showing 0 balance with the wallet address that starts with 14h
That's reasonable. You didn't send money to the legacy address. You sent to the P2SH address.
Now as for Electrum, how did you import it? A private key that starts with 5 will give you an uncompressed legacy address. It will not give you neither P2SH nor Segwit Native / Nested, unless you import a compressed private key (it starts with 'K' or 'L').
There is no uncompressed P2(W)SH address, maybe people have used the non-Segwit version of that in the past, but since this tool was built before Segwit became a thing, I would rule out different private key types as being the cause (as long as this person was aware of this fact).