UTCI Results is NaN, despite being able to obtain other parameters that are used for UTCI calculations

Hi, I am having issues with using an existing script to produce a UTCI map.
Even after making numerous changes to different surfaces in the HB model, i am unable to get any UTCI values in an excel format or even shown visually.

However, i am able to get the Air Temp, MRT and etc, that goes into calculating UTCI. However, I am not too sure why NaN values are turned up in the sensor grid at the beginning.

Would like to request for any advice.