So far, if I update the metafield (which is a list metaobject) with the following as the value, and the existing value of the metafield is blank, it will work tickety-boo, no trouble: ["gid://shopify/Metaobject/26233635050","gid://shopify/Metaobject/...

I am curious to know at what plan level metaobjects are accessible.  I have them in my dev store, but the shop I work for is on the regular Shopify plan, and doesn't seem to have the feature in the bottom of the 'settings > custom data' menu yet, and...