Hmm. That one is a lot more tricky. Without access to the PSD file, my guess is that it may be caused by a layer mask. I've uploaded a new revision that should be more robust dealing with those, so maybe it will be able to load your file now, but I can't guarantee the output will be 100% correct.
I have a task on the project's Trello board to fix that for good (https://trello.com/c/STRvn6Xu) but I will not be able to work on it before Tuesday, and even then, it might takes some time to get it right.