It may not be a law but pharmacies and pharmacists can refuse to fill at their discretion. It’s not uncommon to refuse out of state controlled prescriptions. You can call your prescriber and ask them to call the pharmacy and speak to the pharmacist directly to verify the prescription
I wouldn’t necessarily assume it’s bias or judgement from the pharmacist, they’ll generally want to help but they need to look out for their own license as well. If someone comes in from out of state and they’ve just picked up a prescription from a different chain not through insurance the pharmacist won’t necessarily be able to see that in their controlled substance records if it was out of state. It’s just harder to verify if a prescription is valid and due from out of state. Prescriber/patient from a different geographic region also one of the major red flags everyone’s taught.