Sounds like the project was corrupted somehow.
Any chance you had this project sync'd to Creative Cloud?
I tried to, but it says "cannot connect to server". I also tried to save it to my gallery on my Samsung Galaxy Note 10.1 (the device I am using, just in case you thought it was a different tablet and the solution wouldn't work because of that), but it just loads for a very long time.
I think I had that error message once that was solved by going into PS Touch's options and making sure I was signed into Creative Cloud.
If it can't load the project, then chances are exporting it to the Android Gallery won't work either due to it being corrupted.
Did you have it sync'd? If so, try accessing Creative Cloud from a desktop computer to see if it's there. (https://creative.adobe.com)
No, I did not