yeah I saw that seems to be what happened. Guessing that the game registered the last nuke as having been targeted, preventing any of the other smd from defending.

It seems that if a nuke defence misses the nuke it targeted, all the other nuke defences count that nuke as destroyed. Hence none of them target it and its allowed through despite nuke defence being available

https://youtu.be/lco6jIHAp68