My search results confirm that the OSX App Store does not contain Electrum for download. But there’s Electron Cash (BCH wallet), and something called Electrum Unity, but that has nothing to do with the crypto wallet. If the OP can confirm that he actually download Electrum from there, it is possible that it was a fake wallet that was removed.

https://www.apple.com/us/search/electrum?src=globalnav