The PJ gallery does not accept semi transparencies.
Please use the 'edit it' under the art to upload a pre pixel version or without the trans layers and hit submit again.
You can always link to this hybrid pixel and your project in the description.
This looks so fantastic. Had you used transparent layers for coloring? There's 449 colors, quite a bit. I love it regardless and I hope this goes through hassle-free :D
Best of luck with your project!
I'm really loving the colours but I think some areas could be more refined than sketchy if that makes sense