Compiler Error: Project include paths are parsed as input files rather than paths (Error C4065E)

I am getting a compiler error that indicates that the compiler is viewing my include paths as input files. I am a bit stumped, since this seems to be sometimes caused by spaces in an include path throwing off the compiler, or include paths being placed in unexpected places in the project XML, but I have not seen either of those phenomenon.

My include XML is defined here:

<VariousControls>
<MiscControls></MiscControls>
<Define>USE_HAL_DRIVER,STM32F429xx</Define>
<Undefine></Undefine>
<IncludePath>..\..\..\..\source\nec_decoder;..\..\..\source\segment_display;..\..\application_source;..\..\application_source\board_specific;..\..\..\..\imported\STM32F4xx_HAL_Driver\Inc;..\..\..\..\imported\CMSIS\Device\ST\STM32F4xx\Include;..\..\..\..\imported\CMSIS\Include</IncludePath>
</VariousControls>
</Cads>

The keil project itself lives at:

"C:\NEC_Decoder_Phase_1\NEC_Decoder\application\nec_fan_app\toolchains\mdk\NEC_Decoder.uvprojx"

The rest of the include paths are at:

"C:\NEC_Decoder_Phase_1\NEC_Decoder\application\nec_fan_app\application_source"
"C:\NEC_Decoder_Phase_1\NEC_Decoder\application\nec_fan_app\application_source\board_specific"
"C:\NEC_Decoder_Phase_1\NEC_Decoder\source\nec_decoder"
"C:\NEC_Decoder_Phase_1\NEC_Decoder\source\segment_display"
"C:\NEC_Decoder_Phase_1\NEC_Decoder\imported\STM32F4xx_HAL_Driver\Inc"
"C:\NEC_Decoder_Phase_1\NEC_Decoder\imported\CMSIS\Include"
"C:\NEC_Decoder_Phase_1\NEC_Decoder\imported\CMSIS\Device\ST\STM32F4xx\Include"

No matter which include path I put first in the XML, I get the same compiler error, like so:




"Build target 'NEC_Decoder'
compiling edge_capture.c...
Error: C4065E: type of input file '..\..\..\..\source\nec_decoder' unknown"