Inconsistent autorun behavior between first run and subsequent runs.

Intended outcome:

I would have expected autorun to behave the same on its first run or its nth run, but it appears to do something different on the first run? For the following code I would have expected the autorun to loop until the observable value it's tracking stops changing.

test("autorun", () => {
  const o = mobx.observable.box(0);
  const seen: number[] = [];

  mobx.autorun(() => {
    seen.push(o.get());
    if (o.get() < 5) o.set(o.get() + 1);
  });
  expect(seen).toStrictEqual([0, 1, 2, 3, 4, 5]); // this assertion fails as "seen" is [0]
});

Actual outcome:
The following test case is the actual behavior.

test("autorun", () => {
  const o = mobx.observable.box(0);
  const seen: number[] = [];

  mobx.autorun(() => {
    seen.push(o.get());
    if (o.get() < 5) o.set(o.get() + 1);
  });
  // autorun doesn't continue to run even though a tracked observable value has changed
  expect(seen).toStrictEqual([0]); 

  // triggering the autorun again then causes it to loop (but it has "lost" the value 1)
  o.set(o.get() + 1);
  expect(seen).toStrictEqual([0, 2, 3, 4, 5]);
});

Versions
6.11.0

Start by reproducing the provided autorun test with MobX 6.11.0, then trace the autorun entry point and its scheduling behavior. Add or update coverage for the first-run case; done means the initial run observes [0, 1, 2, 3, 4, 5] without requiring a second observable update.