We got the message that the bunit field belongs to the Asset and Identity framework and therefore should appear in the Additional Fields section of the incident, like Category and Location.
So, Category and Location appear just fine while bunit not, even though it exists.
What can it be?
In the search within Enterprise security, can you run assets macro and review if the assets show bunit column with your expected values.
you can also run the following to check for your specific asset. if this works and if you used the macros in the correlation search, bunit will be populated.
|makeresults | eval src="220.127.116.11" | `get_asset(src)`