Interesting bug... so it works when there's no thumbnail list, but not when it's there...
You know, saving the _current_image isn't necessary (not since version 0.9 anyway), because that's already done in the loop.
Here's something to try... add this line *after* the image loop...
`<?php echo "Still in the image context? " . in_context(ZP_IMAGE); ?>`
If it says true, then it should work. I have a feeling it'll say false, and that's a bug I have to look at...