Cypress Custom Command does not run in test-body

[Shaegi]

I'm trying to write a plugin which compares DOM-Snapshots. To do so I'm writing the element into a file in reading it on the next run.
The functionallity is working fine, however the custom-command does not execute in the test-body, but fails/succeeds in the 'after-all'-Hook.
After crawling through github/stackoverflow issues, I couldn't find a solution for my problem.

The plugin code is the following:

Cypress.Commands.add<'domSnapShot', JQuery<any>>(
  'domSnapShot',
  {
    prevSubject: true
  },
  (subject, options = {}) => {
    return cy
      .task(
        TASKS.getSnapshotPath,
        {
          title: Cypress.currentTest.titlePath.join(' '),
          specPath: Cypress.spec.relative
        },
        { log: false }
      )
      .then((res: { path: String }) => {
        return cy
          .task(
            TASKS.compareSnapshots,
            {
              pathToFile: res.path,
              newElement: subject.prop('outerHTML')
            },
            {
              log: true
            }
          )
          .then(
            (res: {
              oldContent?: string
              newContent?: string
            }) => {
               expect(res.oldContent).to.equal(res.newContent)
              return {
                ...res,
                subject
              }
            }
          )
      })
  }
)

The test code is the fowlloing:

describe('<ScrollContainer />', () => {
  it('matches Snapshot', async () => {
// [...]
    cy.get('body').domSnapShot()
  })
})

In the runner im getting this output:

if I have multiple tests with my custom command, only the last will be executed.
I tried to have a custom cy.wait with alias but it didn't help.
I hope you can help me! Thanks!