Strange, your Yoga tablet should be a Lenovo if it's the one I'm thinking of.
My tablet is also a Lenovo (A10). It has stock Android which has contacts. When I'm out with my phone (LG Thin Q G6) and I add a new number, my tablet at home also updates and adds that number to it's contacts.
The other day I left my phone behind at a friend's and used my tablet to look up his number and call him.
You must have disabled the update contacts feature on your Google account.