Flaky tests of async spring controller with MockMvc

Question

I'm trying to test an async spring controller that returns a DeferredResult:

MvcResult result = mvc.perform(get("/test"))
                .andExpect(request().asyncStarted())
                .andReturn();

result = mvc.perform(asyncDispatch(result))
                .andExpect(status().is(500))
                .andReturn();

This generally works, but it randomly fails on our go-pipeline with ..

Async started expected:<true> but was:<false>

And no other error proceeding this AssertionError. We have multiple tests of this kind. Even when one test fails, others work fine during the same run.

Does anyone have an idea what may cause this flaky behavior? I couldn't reproduce this issue locally.