Hmm. Still can't get it to work. I double click the picture asset, do COMPONENT +, see the Default State, +, make a Hover State. With the Hover State selected, I adjust the APPEARANCE Opacity to 100%. Then with the Default State selected, I set the APPEARANCE Opacity to 0%. When I select the hover State again, the APPEARANCE Opacity is at 0%. I set it to 100%, select the Default State again, and the APPEARANCE Opacity is at 100%. And so on.
Either I'm not doing this right, or something is broken or missing. I've created new documents to test this independantly and it's repeatable every single time. I've noticed that every time I double click the asset, the COMPONENT settings reset.
This is what you need to do. Open the layers panel, click the diamond, select the image and change its opacity. Repeat for the Hover state. Let me know if it worked.