Did you test by exporting or previewing? Make sure the file name/path matches exactly, if you used the debug method I recommended.
This won't work from preview from browser (chrome or other), you have to set the preview to nw.js in project setting.
If you do that you'll see that for preview the file needs to be where you have nwjs installed. Can you confirm your file is there and not the construct folder? (When you export, you'll need to copy it to the export directory)
I'll put together a package capx/exported project for you, but I ran into another issue where textboxes are not captured by the snapshot feature so I'll post it once I put together a workaround for that.