Of course there are many questions about this
Vending machines disintegrate. Of course there are many questions about this, but hardly any helpful answer. It would be really great if the creator could say something specific about how we can fix the problem. Make it easier for everyone. Many Thanks

While editing your zone, try using /zone nodecay true rather then using the GUI, worked for me and stopped the decay.

Also set in config "resistances" "Decay": 1.0,

Hope this helps