ngx-infinite-scroll: scroll is not triggered properly if scrolled quickly

Scroll does not gets triggered if I scroll down to the bottom quickly. The event does not get triggered if I wait at the bottom of the page much beyond infiniteScrollThrottle. However, It gets triggered if I scroll up from the bottom of the page.

But, if I scroll down slowly, the event is being triggered while I scroll down.

Here is the markup I have for the container div

<div class="items-container">
    <div class="items" infinite-scroll
             infiniteScrollDistance="1.5"
             infiniteScrollThrottle="300"
             infiniteScrollContainer=".items-container > .items"
             scrollWindow="false"
             (scrolled)="onLoadMore()">
        <!-- ... items -->
    </div>
</div>

Look at the screencast of the issue (Open image in a new window to see larger version of it)