So I've been playing through the tutorials since I just got this game, and in the 3rd basic tutorial it was going to send a wave to attack me on a timer. The timer ran down, and then nothing happened. The message that told me how to prepare for the wave apparently had its requirements filled, since it turned green and I could continue by clicking it. Then I started playing the intermediate tutorial, and the exact same thing happened. Timer goes to 0:00, message has requirements filled, no enemies spawn.
Is there a setting or configuration I could have accidentally changed to do this? Or is it a known bug? I have no idea. Any help would be nice.
(I have all the DLC btw)