Thanks for the help, everyone. 
It turns out the real issue was in the way I designed the ScoreLabel class; I was trying to instantiate ScoreLabels by static_casting regular Labels to ScoreLabels (in CreateWithTTF, supplemented by init), and apparently that messed up the memory. And thus it’s strange how it worked in the win10 project at all xD
So I did a little redesign, and now it works perfectly! Whether it’s building the game in Debug or Release, or deploying it through the cocos console, it works as it should!
Credit to @Nuno147 for finding and showing me the issue.