CppParser.ParseFiles() functions differently when run during a pre-build event in VS19, but works normally elsewhere

I am developing a small preprocessor for a game engine that I am working on with some friends, and we are using CppAST.Net in the preprocessor to autogenerate some files for runtime reflection.

The development of the preprocessor was going well, until I tried to run it during a pre-build event in visual studio where it wouldn't parse all of the files that I gave it. When run from the debugger or from a local published version of the application the program generates the AST in 30-40 seconds, finds 19 classes, 4 of which have the reflectable attribute, and generates 4 files for each of those classes (16 in total). But when the application is run during a pre-build event it only takes 5-6 seconds, finds 8 classes (non of which are reflectable) and generates no files.

I have been testing and debugging for the last week and I am completely at a loss. If anyone has any ideas on what this could be any help would be appreciated.

Some of my suspicions that I have yet to be able to prove/disprove is that the VS19 build output cmd prompt may have some different env variables that prevent certain functions from being called or are blocking certain .Net libraries. I have also checked my output, and there are no errors to be found.

Start at CppParser.ParseFiles() and compare its behavior when launched from the debugger or a local published application versus the Visual Studio 19 pre-build event. Inspect the pre-build process environment and output, especially the differing parse times and class counts. Done means the pre-build invocation parses the same 19 classes, identifies the 4 reflectable classes, and generates all 16 files.