Sorry to hear about the frustration and not being able to get this working like expected. I’ve had no problem getting this functionality in the past, so there really shouldn’t need to be a need to pre-crop these images, however without being able to see the specific situation it’s hard for anyone in the community to help you out.
You mentioned including a public link but I don’t see it—would you mind generating one so I can take a look? In the meantime, here’s a my published site and read-only link showing this functionality on a quick test project for reference:
Basically the only change I needed to make after defining my grid container height was to set my dynamic image to
height: 100% and change the
Hopefully that helps, but if not I’d be happy to take a closer look at your exact implementation.