It's because I'm using WinForms within visual studio to build it, and for some reason ClickOnce deployment is a buggy system with too many variables to be reliable. I'll try to upload a zip of the post-install files so that installation isn't necessary.
Edit: New release uploaded, and circumvents installer completely. I apologize for the issues, this is the first game I've built and released, and I'm still trying to get the hang of things. Enjoy the new features!