I am working on an existing code base, and needed to move a single include from a derived class to its parent. I then get fatal error C1083: Cannot open include file: 'VClient.h'.

The parent and child header files are in the same folder, and I have successfully included VClient elsewhere in this folder. The included file is within a separate library folder.

Stranger still, it all compiles just fine on Linux.

So far I have tried cleaning the directory, restarting VSCode, and putting #include "VClient.h" within one of the includes the parent already has.

Strangely, I can include other files in the parent successfully, however any references those new files have to the library folder subsequently break.

This is a CMake project using QT if that makes any difference.