Saving a custom label (CFStringRef) for contacts always reverts text "Home"

Question

When saving phone number "tecnical" as a custom label to Contacts with ABRecord, the label for "technical" reverts to label "home" when viewed in contacts. Everything else saves as expected. The preview shows correct string "technical" but then changes when saved and viewed in Contacts

//Phone number(s)
const CFStringRef customLabel = CFSTR( "Technical" );

ABMultiValueRef multiPhone = ABMultiValueCreateMutable(kABMultiStringPropertyType);
ABMultiValueAddValueAndLabel(multiPhone, (__bridge_retained CFStringRef)@"000000000", kABWorkLabel, NULL);
ABMultiValueAddValueAndLabel(multiPhone, (__bridge_retained CFStringRef)@"00000000", customLabel, NULL);
        ABRecordSetValue(person, kABPersonPhoneProperty, multiPhone, nil);
        CFRelease(multiPhone);

Expected behaviour: Second phone number saves with label: "Technical"

Actual behaviour: Saves as label "Home"