Hi both,
This sounds similar to the bare metal issue reported by @JohnnyK in Mbed Keil Studio Cloud IntelliSense "fake" (invalid) errors and header problems (mbed.h error) - #6 by JohnnyK.
If so, my suggestion here might work around it: Mbed Keil Studio Cloud IntelliSense "fake" (invalid) errors and header problems (mbed.h error) - #8 by mgordon01.
Matt