Had not been in my electrum wallet for over a year. When I went in balance showed "0". Made a small purchase to see if it would show up. No luck. Did wallet new/restore using seed phrase. No luck.
I would update the wallet.
Download the new version here
https://electrum.org/#downloadDid you generate the address for this transaction just before sending it? Are you sure you are in the correct wallet? Derivation path and seed?