Haxe script keeps resetting - please help

I don’t know if this is normal or whether it’s some sort of bug, but I can’t seem to manually edit any of the Haxe scripts that come in the armory-templates pack. Specifically, I am testing the new PhysicsBreak class and I wanted to change the impulse threshold needed to cause the object to shatter. I was able to add this line:

@prop var fractureImpulse:Float = 4.0;

and the property shows up in the Armory Traits tab, but when I run Armory to test and come back, it has all disappeared. If I check the script using Edit Script, the script has been reset to its original contents.

What is going wrong? Why is this happening?

Thanks in advance for your help.

PS: Using Armory 0.6 with bundled Blender 2.8