It might be something about how Voidbound uses Vulkan and/or Live2D. My meandering searches last night pointed towards nw.js programs using Vulkan rendering between processes, which might seem weird to an anti-cheat program. (Or it could be me not knowing enough about how these programs work.) I don't have another RPG Maker MV/MZ game handy that uses them, though, and even if I did no way to determine what specific thing might be causing problems.
I can confirm that you can't start Voidbound while Star Wars Squadrons (which also uses EAC) is sitting at its main menu. 4 nw.js instances appear in Background Processes but it doesn't make it to showing a window.
Ren'Py games with Live2D don't seem to be affected, FWIW. Neither do "regular" RPG Maker MV/MZ games.
At least the workaround is easy: only play one game at a time.