Z-Wave JS suddenly stops including devices with S0

Recently I have been playing around with different stick to test if it would be better than my old Gen 5 stick.

I finally went back to my old Gen 5 as the other new sticks seem to give more trouble and make my network slow, where I don’t have this with my old stick. Everything is running just fine again.

One thing I don’t understand is, why after including many devices with S0 security (I know it’s heavier on traffic, but prefer some security over none), it stops including devices with S0 security. At first it worked just fine. No issues at all. After about 20 devices, it stopped including with S0. I tried it multiple times, but it will not do that anymore, while it worked just fine before.

What could be the reason the S0 inclusion suddenly stopped working? I use Zwave JS. Not Zwave JS UI.