I had this same problem, but was able to get it to work.
Use these instructions Build flip cards with transforms - Webflow University Documentation and then make sure to leave the z-index as auto on both the front and back cards.
I had this same problem, but was able to get it to work.
Use these instructions Build flip cards with transforms - Webflow University Documentation and then make sure to leave the z-index as auto on both the front and back cards.