1. Restarting the computer... DO NOT start Ledger Live, just start Electrum and see if it detects the device
I would go for this as suggested by HCP as well.
Fresh restart and connect your Ledger wallet. Unlock it with your PIN, browse and open the Bitcoin application. Only after you have done that open your Electrum software and see if it gets recognized.
I never had to run Electrum as an administrator and I use Ledger Live with it as well but you just can't have both running at the same time.
Are you opening Electrum from a shortcut on your desktop? Try running it directly from the location you installed it on your hard drive.