Black line appears under image block when using Elementor Plugin

Black line appears under image block once I activate the Hover and opacity option in the Elementor Plugin; I’ve created an image grid of four horizontal images, with links. The moment I activate the hover and opacity option I get a black line showing up (at the bottom of the image box) when I scroll over the image.

Not too sure if there is something I am forgetting to do here, would like to get rid of the black lines.

Thanks for reading!

Katherine