I cannot see all my contacts

I can only see a subset of my contacts on WhatsApp. I have read the FAQ's, and ensured my phone settings allow Contacts to be shared to WhatsApp, and many of them are (248 out of 1033).

When I use the Share WhatsApp function, it can then see all 1033 contacts.

But somehow when adding contacts to groups, it only sees 248 of them.

I have checked international phone format, and that is ok.

Quite confused, and any insights greatly appreciated.