I think that missile may have been too quick for the interceptors. By no means am I am expert, but it looks like the fusing action happens just after the closest point of approach.
The interceptor system tries to follow the path of a missile using a radar on the ground. Then it calculates where the missile will be in a few moments. They send their own missiles to that point to explode.
By zig zagging slightly and changing direction the AnsarAllah missile diverged from where the interceptor system expected it to be. It only has to slightly change angle at that high speed to be somewhere different than the interceptors expect.
Thus the interceptors explode somewhere the missile was not.
What type of missile do they have that has a MaRV?
Iranian stuff. Allegedly this is a Palestine 2 missile. They claim it to be hypersonic though some doubt that claim. It did beat the Israeli interception system so it has got something going for it.
Pretty sure they have layered defense as well, so it beat multiple systems.
