Entering China with a Canadian Passport as a Hong Kong resident

My family and I will be flying to Shanghai from Canada for 10 days. My mom was born in HK but has been a Canadian citizen for over 40 years. She was advised by some visa centres that the requirements have changed and that she can no longer apply for a Chinese entry permit as a Canadian citizen/passport holder as she is a HK resident. And that this may also apply to other members of our family because my parents are first generation Canadian. Is this true? And if so, how would we go about entering China if we do not get it?

Thanks