I entered one of the many addresses listed under "Addresses" in Electrum, into Coinfloor, but it said "Address is not valid"
I am not an expert in electrum wallet but here are some threads I found here in the forum that could(maybe) help you fix the "invalid address" you are getting. if you are still skeptical you can wait for a more knowledgeable member to help you with the invalid address you got from electrum. sorry if I am not much of a help.
Electrum Generating invalid bitcoin addressBeginner Question "The provided Bitcoin address is not valid"