I created a query and then added a result set to the Start Center for our custom application. In the Result Set portlet the query was chosen but no fields were displaying in the Available List or objects in the Object List.
The reason for the empty fields was ultimately due to a database length field issue on two objects: RESULTSETCOLS and RSCONFIGSELECT. The APP attribute field length is 10 but our custom application name length was 11.
Increasing the attribute length for APP in RESULTSETCOLS and RSCONFIGSELECT followed by a database configuration corrected the problem which resulted in the Object List and Available Fields list displaying the appropriate information.
This was in Maximo 18.104.22.168 so the problem may already be corrected in a patch.