How to get the next element from monix observable?

I have a stream of data that I casually log, but at a certain state of my program I need the data from the stream, not the latest observed up to that point(I can do that), but the newest one after:

val dataStream : Observable[Data] = ...
dataStream
 .doOnNext(logger.trace(_))
 .subscribe()

// ...
// at some state of program later:
// ...
def awaitOneElement(Observable[Data]): Data = ???
val expecting: Data = awaitOneElement(dataStream.filter(...))

How do I implement def awaitOneElement(Observable[Data]): Data = ????

I understand it's probably idiomatically incorrect, but that dirty synchronous waiting is exactly what I need. I'm fine with Observable[Data] => Future[Data] too, will wrap with Await on the next step.

My solution:

  implicit val scheduler                     = mx
  val pendingPromise: AtomicReference[Option[Promise[A]]] = new AtomicReference(None)
  val lastSubject: ConcurrentSubject[A, A]   = ConcurrentSubject.publish[A]

  o.doOnNext(a => if (pendingPromise.get().nonEmpty) lastSubject.onNext(a))
    .subscribe()

  lastSubject
    .filter(filter)
    .doOnNext(a => pendingPromise.getAndSet(None).map(_.success(a)))
    .subscribe()

  def getNext(duration: Duration): Try[A] = {
    val promise = Promise[A]()
    pendingPromise.set(Some(promise))
    Try(Await.result(promise.future, duration))
  }
}

When getNext is called, a Promise is created and future is returned. When the desired event occures in Observable, the promise is filled and removed.