Ok, I made a script which is an example of how this is works (It works i tested it) here is the script:
And I figured out what was wrong. You forgot to see if the amount of players was 0 (when the server first starts)
while wait(1) do
local Players = game.Players:GetPlayers()
if #Players ~= 0 then -- before you didn't check if the amount of players is 0
local RandomPlayer = Players[math.random(1,#Players)]
print(RandomPlayer)
end
end