I am using the action "Update Multiple Items" in my workflow to update the metadata in another library but somehow I am not able to see all the columns in "Fields to update" section when I click on the dropdown next to "Field" column. I tried all the different options but no luck.
ah question on this - is your list built from a template? what version are you on for nintex workflow?
I have identified a similar issue with delete multiple items action which has been raised a defect with nintex awaiting a fix - maybe you can contact support and see if it is the exact same thing?