Hello, Catholicans,
Thank you for your response.
It seems the main reason is in next custom:
.products-loop .product, .products-slider.second-initialized .product-slide { transition: all .2s ease-in-out; }
We recommend you remove it fully and check it then. In case the issue will be fixed you can try to leave only next code and check again.
.products-loop .product { transition: all .2s ease-in-out; }
= removed the transition property for products shown in sliders.
Kind Regards, 8theme team
