Use the prpcUtils script found in the /scripts/utils folder of the deployment image. There is a setting for the utility script, ‘expose.reindex=true’, that specifically regenerates declarative index content.
You can also refer to the PDN article given below for general information on the column populator:
Don't leave 'expose.declareindex.accessgroup' or 'pega.user.username' property empty in your prpcUtils.properties file, define any one of the properties and run the utility. It should work for you to get old workobjects listed in index table.