Injecting mobx objects into global window loses observability of objects in Cypress test

[Philip-Grozdanov]

I have a SAP UI5 typescript application and I have the following cypress test:

describe("Auto schedule", () => {

  beforeEach(() => {
 
  });

  describe("", () => {
    beforeEach(() => {
         clock().execAsOn(() => {
      cy.visit("index.html", {
        onLoad(win) {
          const empSchedule = new EmployeeScheduleModel(
            new Date(),
            new Date(),
            new EmployeeModel(),
            ModelCollection.empty()
          );
          console.log("Before load is observable" + isObservable(empSchedule));
          // Use defineProperty to make it non-configurable/enumerable
          Object.defineProperty(win, "_EMP_SCHEDULE_", {
            value: empSchedule,
            writable: false,
            configurable: false,
            enumerable: true,
          });
          console.log("After load is observable " + isObservable(empSchedule));
        },
      });
      cy.get(".sapFAvatar", { timeout: 500000 });
      cy.get("#gifContainer", { timeout: 500000 }).should("not.exist");
    }, this.now);
    });
    it("correct data", () => {});
  });
});

Both logs show that "Before Load is observable" and "After load is observable " are true .
EmployeeScheduleModel is makeAutoObservable(this); in the constructor looks like this :

export class EmployeeScheduleModel implements IEmployeeScheduleModel {
  private _employeeNeedsNotification = false;
  constructor(
    private _start: Date,
    private _end: Date,
    private _employee: EmployeeModel,
    private _shifts: IModelCollection<IEmployeeShiftModel>,
    private _absences: EmployeeAbsenceModel[] = [],
    private _holidays: HolidayModel[] = [],
    private _placeholders: PlaceholderModel[] = []
  ) {
    _shifts.getAll().forEach((shift) => shift.attachTo(this, false));
    makeAutoObservable(this);
    reaction(
      () => this._shifts.getAll().map((shift) => this.anyShiftDataChanged(shift)),
      () => (this._employeeNeedsNotification = true)
    );
    this._holidays = _employee?.holidays;
  }

}

Once the application starts , in the backend I read the object from the window like this

const empSchedule = window._EMP_SCHEDULE_;
console.log("Is observable: ", isObservable(empSchedule)); 

but now Is observable gives False ! Why when I inject objects in the context window then they are no longer observable? Is there a way to make my object keep being auto-observable from the context window?