They all popped out around 4 days after left directly in rockwool cube. This time I haven't left the seeds soaking in a glass of water for a while like I used to and they turned out just fine. So I'm sticking to this method from now on as I haven't lost any seeds since using it.
This grow I'm using CANNA Terra Professional as substrate for the first time instead the soil mix I've been using since my first grow.