main product images sometimes not displaying

Hi there

Occasionally the main product image does not show when looking at a single product. All images show ( variations etc ). It looks as if the image has loaded but its just not on screen. Reloading the page fixes the issue.

Any ideas of where I need to start to debug this. Ive made a bunch of changes all at the same time. GeneratePress and WPML.

cinda.co.uk

Thanks