Covid-19 Testing

I have been billing for Covid-19 lab tests with Z03.818 or Z20.828 with mod CR. Today an insurance company told me that in order to have a patient's co-pay waived, I need to use U07.1. I explained I cannot use the U07.1 unless the patient actually has Covid-19. Am I understanding this incorrectly? Other insurances I have billed are waiving copays with Z03.818 or Z20.828.

Thanks!