try disable minify script? see if works ... if not.. there might be a event sheet problem.. or a file in your game that will just take a bit longer to load.. which can seem to be stuck at 70% cause your bandwidth is to slow.. i had similar problems lately... was only a bandwidth problem for me... not sure on ur side
The NW.js exporter exports all files in a way so an internet connexion is not needed, so bandwidth is out of the question. As for the event sheet, it is also out of the equation as this is about the initial l8ading of the game which will load things up but won't interpret them (unless maybe a custom loader is being used and cannot load, but I doubt it)
I think I saw a similar issue in the past, will try to find it again.
I think I found it https://www.scirra.com/forum/how-to-node-webkit-for-linux-and-mac-2015_t127201