I am also seeing the same after updating to version 23.4.8

a quick/easy way would be to create row totals and then hide the individual measures from the visualization

if you are just trying to average a single column/dimension, and have access to LookML development, you should just be able to use an “average measure”: https://docs.looker.com/reference/field-reference/measure-type-reference#average

maybe try using a table calculation to concat instead, along with the table calc specific function “to_string”