Chrono file note found: Fatal Error

Hi
I am seeing a strange issue here with compilation

Working scenario
main.cpp
#include “mbed.h”
#include “psa/crypto.h”
etc
i am able to correctly call all the psa functions ( i have the necessary macros enabled for my target)

Failing Scenario
i move all the cypto functionalities and calls to a separate file - say cryptofunctions.h/.c
Include it in main.cpp

During compilation, i get following error

[Fatal Error] Kernel.h@27,10: ‘chrono’ file not found
[ERROR] In file included from .\cryptofunctions.c:2:
In file included from ./mbed-os\mbed.h:22:
In file included from ./mbed-os/rtos/include\rtos/rtos.h:28:
./mbed-os/rtos/include\rtos/Kernel.h:27:10: fatal error: ‘chrono’ file not found
#include
^~~~~~~~
1 error generated.


What is this error and how to address it?
my target is PSoC6 WIFI BT Kit