I've made some fractal ice cap images for use with Fractal Terrains worlds as image overlays. However, there's a problem - as soon as I add clouds using the Terraformer 0.5 cloud maps, the ice cap overlay becomes translucent. If I hide the clouds overlay, the ice caps become opaque again.

The ice cap color image is currently solid white. The opacity image is solid white for most of the ice cap, gray at the borders, and black elsewhere. Both images are 2048 x 1024 width by height, and are loaded as png files. The opacity slider is set to 100% (solid) for both the ice cap overlay and the clouds overlay. The ordering of the cloud map and ice cap overlays in the overlay window list doesn't seem to make any difference.

Is this a bug, or have I misunderstood something?

Thanks in advance for any suggestions