I've downloaded your workspace. I've tried to build the workspace.
App1-Main goes through the Application build phase but doesn't start the compile phase.
I see one "Additional Include Directories".
AppX-BitmapUtility goes through the Application build phase but fails at the compile phase with:
..\App1-Main.cydsn\SpiMasterTask.c:5:24: fatal error: cy_scb_spi.h: No such file or directory compilation terminated.
I see no "Additional Include Directories"
As you indicated, the workspace will not build but I can't get directly to your stated problem. hit other problem first.
Is the aPOC project used for anything?
Sharing content between projects. I've done it before. It can be done but is tricky. I have a PSoC6 project I placed in the Code Sharing forum. It uses shared .c and .h files across two projects. PSoC6 BLE Beacon and Scanner Creator projects. PSoC6 BLE Beacon and Scanner Creator projects.
I can easily share .c files. I just have to "Add/Existing Item..." from the other project.
The trick is #include .h files referenced in the .c file wants to be local to the project. To fix this I had to add the source project directory to the "Build Settings.../CM4.../Compiler/Additional Include Directories" for the project that requires the shared .c and .h files.
I hope this helps.