Infinite loop from Buffer and ReplaySubject interaction

[Norskan]

Which library version?
Bug occurs with 5.0 and 6.0

What is the use case or problem?
We have a continuous stream of data that we want to process in chunks. To archive this we a buffer that we can flush if needed.

public static IObservable<IList<TSource>> FlushableBuffer<TSource>(this IObservable<TSource> source, int max, ISubject<Unit> manualFlushSignal)
    {
        var bufferOverFlowFlushSignal = source.Skip(max - 1)
                                              .Select(_ => Unit.Default);
        var mergedSignals = manualFlushSignal.Merge(bufferOverFlowFlushSignal);

        return source.Buffer(() => mergedSignals);
    }

This behavior works fine for BehaviorSubject and Subject but with ReplaySubject we get an infinite loop when the buffer is full.

I wrote some tests to illustrate this issue:
ReactiveReplaySubjectFlushableBuffer.zip

Best Regards
Simon