Odd crop behaviour in Gigapixel

I am not sure if my experience is a bug or something I am doing! From time to time I use Gigapixel in crop mode, normally only increasing size by 2x. Lately I have been experiencing an intermittent fault that appears to only occur when processing a batch… If I select a portion of my image by crop (for instance a bird) over several photos and process them as usual some of the resulting images are not as I set the crop, for instance the bird may now only partly in the frame or not at all. The process seems to have adjusted the crop setting. As said this does not seem to occur every time nor when using on single images. I should perhaps add that these are usually significant crops.
I have reported this to Topaz but no solution offered at present other than just use non-batch processing. Anyone else experienced this phenomenon?