assertFalse does not work on Android Oreo 8.1

[EQXTFL]

The following test works fine on API 22 (Lollipop) to 26 (Oreo 8.0) and also 28 (P). But for some reason it does not work on API 27 (Oreo 8.1).

1. Open Google Map
2. Display Toast
3. assertTrue("toast message");
4. Close Google Map
5. Open Google Map
6. assertFalse("toast message");

It always fails at 6. Any ideas?

[EQXTFL]

Update - it works fine again on Android Pie.