I vaguely remember this happening when trying something out with nw.js exports. As you said, it leaves processes running in the background that then prevent the game launching. So in theory, it should always work the first time after restarting the pc. Since I never used the greenworks plugin I doubt that it causes the issue.
I found this 3 year old (and fixed) issue, it seems that may have creeped back in github.com/nwjs/nw.js/issues/6059
And a newer one (I think there are actually several)
github.com/nwjs/nw.js/issues/7122
You could try the solutions from there.