When exporting in NW.js (or using it as preview browser) the custom cursor image disappears when you move the mouse outside the game window and move it back.
Just one object to change the mouse cursor (a sprite 32x32). To reproduce the bug, preview in NW.js (or export the project) and move the cursor outside the window or on the resize area (where the cursor change to the resize arrow), then move it back on the game window. If you export the game without the "resizable window" option it works fine.
Windows10 ver1803 64bits
R259 64bits, nwjs v0.31.0
Develop games in your browser. Powerful, performant & highly capable.
I think it's this NW.js bug.