The reason you're transaction hasn't been processed yet is because of the huge pile of unconfirmed transactions in the blockchain mempool at the moment. To help you understand the current situation and analyze why your transaction hasn't been processed yet follow my points:
1) If you see here:
https://fork.lol/pow/hashrate you'll notice that at the moment and since several hours more than 50% of the mining power has shifted / moved to BCH temporarily cause they find it more profitable at the moment to mine. Thus with less mining power, it's taking longer to mine a block until Bitcoin's difficulty rate reduces (which it will in a few hours). When the difficulty rate reduces, Bitcoin will again be profitable to mine and mining hashpower will move back.
2) Now since more hashpower has shifted, the number of bitcoin transactions have piled up since they haven't been confirmed in the next block which you can see here:
https://blockchain.info/unconfirmed-transactions (about 161,000 unconfirmed transactions). This is leading to people having to pay higher miner's fee to get it included in the next block that gets mined.
3) Now because of higher mining fees, the current fastest transaction fee is 850 satoshis/byte to be included in the next block which you can see
https://bitcoinfees.earn.com/ here, where as the fee you've paid is 351.77 satoshi/byte. Hence it may take hours to have your transaction confirmed unless you use Replace by fee in electrum to pay a higher fee (about 850 which is the current recommended) to be included in the next block.
If you can't afford to pay such high fees I suggest you wait it out since it's unfortunate that many transactions are pending and the mempool is filled up. Also most transaction accelerators are also not accepting new transactions cause they've too been queued up.
So basically I doubt this has anything to do with Electrum's version.
