I can see that there exists a CSS property that causes this problem. I have no idea what this is good for, if you remove this the widget loads fine:
.oh-swiper-slide {
width:unset!important
}
I can see that this was added a few weeks ago to fix some other display problems:
@florian-h05 Sorry for pinging you, but could you please have a look at this? The swipers of this widget are broken because the “width: 100%” style property of the swiper slides are unset. Is there a way to somehow override this?