Very sad OCaml module situation

file.re

/* Problem1 */

module Y = {
  /* Why is this include needed? */
  include File2.Common;
  type item = {x: string};
  let renderItem x => x.item.x;
};

module MyList = File2.CreateComponent2 Y;

module Test = {
  type x = {
    abc: string
  };
};

/* Cannot use a type from another module */

module Z = {
  include File2.Common;
  type item = Test.x;
  /* this works:
    type x = {
      abc: string
    };
  */
  let renderItem x => x.item.abc;
};

module MyList2 = File2.CreateComponent2 Z; 

/* Bonus case - why? */

module MyList3 = File2.CreateComponent2 {
  include File2.Common;
  type item = { abc: string };
  let renderItem x => x.item.abc;
}; 

file2.re

module Common = {
  type section 'a = {data: 'a};
  type renderBag 'a = {item: 'a};
};

module type Impl = {type item; let renderItem: Common.renderBag item => string;};

module CreateComponent (Impl: Impl) => {
  let createRenderBag ::item => item;
};

module CreateComponent2 (Impl: Impl) => {
  /* Why is this include needed? */
  include Common;
  type b = Common.section Impl.item;
  let createElement sections::(sections: array b) =>
    Array.map (fun x => {"data": x.data}) sections;
};