Hi,
I'm using px2d v1.1.4.3 on windows 10 and it won't save.
I tried to save as PNG by pressing the number key 4, but the file does not save.
I've also tried saving as a px2d file, but that doesn't work either.
Currently, the software does not support translucency. So, if you need the shadow, finally process it in the image processing software. For example, Photoshop. Change the shadow to semi transparent. Remove the shadow component if it is not needed. I usually end up dealing with shadows. In Photoshop.