Combination AFCI's keep tripping
New construction. 320 service. 3 AFCI's keep tripping in panel A. Panel B no AFCI's are tripping. Hooked up an AFCI tester from Siemens. No load, and the tester still has a reading that there is a load or a problem (ie nuetral to ground). Tested contunuity nuetral to ground no problem there. Swapped out old AFCI's to brand new AFCI's and still trips. Switched the circuit to the other phase and reads fine and does not trip. Regular breakers do not trip. I have come to the conclusion that there is a bad phase from the street to the service. Just curious if anyone else has had such a problem or heard of this. Stupid AFCI's. Thanks.