how to get the MCU version number ? MCU_API_get_version seems to give me different result

[CChon.0]

sfx_u8* version_m;
sfx_u8 size_m;
retr_err =	MCU_API_get_version(&version_m,&size_m);		

This works for

retr_err = ADDON_SIGFOX_VERIFIED_API_get_version(&version_a,&size_a);
 
retr_err = RF_API_get_version(&version_r,&size_r);

but not for MCU_API_get_version

Please help. Thank you