Ionic 4 virtual scroll is blank when scrolling programmatically

I was able to scroll to letter “Q” programatically using “positionForItem(index)”
However after a few clicks the virtual scroll becomes white/blank.
It will only redraw when scrolling up or down.
I tried every possibile way to force redraw: zone, app.tick, markdirtytail, markdirty(0,all), etc.
Any idea if is it possible or is it a bug?

        this.zone.run(() => {
            this.MainScroll.nativeElement.positionForItem(i)
                .then(res => {
                    this.content.scrollToPoint(0, res - 50).then(res2 => {
                        //this.MainScroll.nativeElement.markDirtyTail();
                        //this.MainScroll.nativeElement.markDirty(0, this.allItems.length);
                        //this.app.tick();
                    });

                })
                .catch(logError)
            ;
        });

Did you find a solution for this? I am facing a similar issue when I scroll to top.

Same here… When I scroll down the rows are not rendered. There was the property bufferSize in the previous version (ionic 3) used to optimize the scrolling. In the version 4 seems it’s been removed…
It would be a good workaround limit the scroll speed, but I have no idea how to achieve it…