Can states just be like “no, we won’t act on a legal subpoena/warrant/child custody battle from this other state”? Maybe it’s common, I don’t know, I’ve never heard of such. Other countries, yes, but not other states.
Normally no, they can’t since that would fall under the Full Faith and Credit Clause of the Constitution. However, California appears to be set to dynamite one of the fundamental bases of federal and should eventually expect other states to reciprocate.
You’re a Californian woman who gets child support from your ex who lives in Florida? Too bad, looks like that won’t be happening.