

No, never happened.
This is I-5, the main highway in CA and the entire West coast. It is full of shipping and business commuters 24/7, and even a minor shutdown likely causes millions in losses.
FTA:
Newsom said safety concerns over the event forced state officials to close a portion of the busy Interstate 5 near the US Marine Camp Pendleton base on Saturday. […] The California Highway Patrol said in a statement the military event would involve “live ammunition being discharged by the federal government over the freeway” and made the call to temporarily close a portion of the freeway
It sounds like the gov. just said “we’re doing this, you gotta figure it out now”.
I have a different take: this is all according to plan. It normalizes the idea of live fire over and around US infrastructure. This normalization is meant for the troops, not the public. … though it is a side benefit.