user75001: How does importing private keys work?
I have previously imported the private key for a 1Archive... address into Bitcoin Core and noted then it added an address like 1AXbRq...  and I didn't follow it up further.
Today I have exported the private key for a 3... address from Bitcoin Core and imported it in Electrum. Electrum adds a 1... address and doesn't see any of the transactions.
How does this work? I understand that there is an underlying 1... address behind a SegWit address but how would I spend any BTC if it is not showing in my wallet balance? What else should I do?
If there is an answered question for this already on Bitcoin.SE I could not find it.
My private key begins with L.

user7272: I suspect you can import it directly from the console within Electrum (based on this PR). Currently, Electrum does now allow importing individual p2wpk inside p2sh addresses (the 3 segwit addresses). You can, however, still import an entire seed by using a BIP49 derivation path.
Try running the following in the electrum console:
key = 'your_key'
txin_type, secret, compressed = bitcoin.deserialize_privkey(key)
wif2 = bitcoin.serialize_privkey(secret, compressed, 'p2wpkh-p2sh')
print(wif2)

Then import the wif2 which it prints out

user5273: Prepend "p2wpkh-p2sh:" to the private key before importing it into Electrum. For example:
p2wpkh-p2sh:5Kkzs8XrJNAmf9VQDFeGBfaRvSByAvPK6DbDXw5BVqswWaXSG2Y

75001: <p>How does importing private keys work?</p>

<p>I have previously imported the private key for a 1Archive... address into Bitcoin Core and noted then it added an address like 1AXbRq...  and I didn't follow it up further.</p>

<p>Today I have exported the private key for a 3... address from Bitcoin Core and imported it in Electrum. Electrum adds a 1... address and doesn't see any of the transactions.</p>

<p>How does this work? I understand that there is an underlying 1... address behind a SegWit address but how would I spend any BTC if it is not showing in my wallet balance? What else should I do?</p>

<p>If there is an answered question for this already on Bitcoin.SE I could not find it.</p>

<p>My private key begins with L.</p>
 7272: <p>I suspect you can import it directly from the console within Electrum (based on <a href="https://github.com/spesmilo/electrum/issues/3620" rel="nofollow noreferrer">this</a> PR). Currently, Electrum does now allow importing individual p2wpk inside p2sh addresses (the 3 segwit addresses). You can, however, still import an entire seed by using a BIP49 derivation path.</p>

<p>Try running the following in the electrum console:</p>

<pre><code>key = 'your_key'
txin_type, secret, compressed = bitcoin.deserialize_privkey(key)
wif2 = bitcoin.serialize_privkey(secret, compressed, 'p2wpkh-p2sh')
print(wif2)
</code></pre>

<p>Then import the wif2 which it prints out</p>
 5273: <p>Prepend "p2wpkh-p2sh:" to the private key before importing it into Electrum. For example:</p>

<p><code>p2wpkh-p2sh:5Kkzs8XrJNAmf9VQDFeGBfaRvSByAvPK6DbDXw5BVqswWaXSG2Y</code></p>
