A couple of months ago, the One Click Tool stopped working for me. It didn't replace any costumes when I wanted (no upk files was created in the mod file) and I couldn't view with the tool any costume in 3D Viewer.
I stopped playing Blade & Soul a while and came back with the Archer Patch recently.
Looking on this forum and on reddit to find out how to fix my bug...
Tried a couple of things like ownership or antivirus exceptions, nothing was fixing it.
Just now, I just reinstalled Node.js, an important "programming software" for this tool to work.
Tried to view in 3D, it worked
Tried to replace a hair, it worked, a upk file was created.
The too finally worked again.
TL;DR - I fixed my bugging tool just by reinstalling Node.js