I have certainly read explanations for this purchasing overseas activity; it was explained that official economic policy was to encourage the investment of foreign earnings abroad, as their return to China would cause problems, inflation primarily.

Overseas property purchasing was very noticeable before the Hong Kong handover, notably in Vancouver, Canada - which was more amenable to granting citizenship IIRC and there being an established Chinese community.

I don't think it is ineffective capital controls out of China, it is that foreign earnings are not fully declared.