Custom content doesn't actually use the real %LOCALAPPDATA% but rather what seems to be a hardcoded path using the systems PC Name?
%LOCALAPPDATA% has all the expected save game data etc you'd expect, so it it does use this for save data.
However when we activate custom content and it says that we should add our content to the %LOCALAPPDATA%/Votv/Assets/tv you might not be able to get the assets folder at all.
Instead what the game did, is create a "fake" Appdata using the pc name. In my case it created a new folder path under Users: (PcName)/Appdata/Local/VotV/Assets/tv
Viewing post in Voices of the Void 0.8.2 Bug Reports
That's weird my save data and custom content folders are all located in the same folder which is "C:\Users\"myname"\AppData\Local\VotV". It has always been this way as well at least as long as i have played the game which is about a year. I think you can set your own custom content file path in-game in the settings.
I'm glad that it works for you, but that's not the point of a bug report.
The default settings, aka blank asset path, leads to the game creating and searching for a false Appdata path.
Meaning there is some bug or discrepancy in how the game gets Appdata while accessing custom content, vs how the game gets Appdata while accessing save data etc.