why does the function return what it needs in one place, and in another it returns 'undefined'?

Question

I wrote a test

import {actions} from "./usersPageReducer";
import { usersAPI } from "../api/api";

jest.mock("../api/api");

const usersAPIMock = usersAPI;

usersAPIMock.follow.mockReturnValue(() => ({ data: true }));

describe("follow", () => {

If you remove the comment we get, what we need response = { data: true }

  /* const response = usersAPIMock.follow(1, "true");
  console.log("res", response); */
  it("follow", () => {
    const dispatchMock = jest.fn();
    
    const followTest = (userID: number) => {
      
      return async (dispatchMock) => {
        dispatchMock(actions.buttonDisabledAC(true, userID));
        
        const result = await usersAPIMock.follow(userID, "true");
        

But here, for some reason, it returns 'undefined'

        if (result.data === true) {
          dispatchMock(actions.followAC(userID));
          dispatchMock(actions.buttonDisabledAC(false, userID));
        }
      };
    };

    const thunk = followTest(1);

    thunk(dispatchMock);

    expect(dispatchMock).toBeCalledTimes(3);
  });
});

Explain why this is happening, what am I doing wrong? And how to do it right?