Rebuilding A Domain Index

I have a table in my application that has the following structure

Create table EVENT (project_id number, DISC_CMPLNT_TX clob, MAINT_ACT_TX CLOB,LGBK_CMT_TX VARCHAR2(1000 CHAR))
PARTITION BY RANGE (project_id)
(PARTITION pmax VALUES LESS THAN (MAXVALUE));

I have created the below preference on the three columns of the table.

begin
ctx_ddl.create_preference ('skipJoinLexer', 'BASIC_LEXER');
ctx_ddl.set_attribute ('skipJoinLexer', 'skipjoins', ';:.,()<>*"''#-');
ctx_ddl.create_preference ('logbookTextDS', 'MULTI_COLUMN_DATASTORE');
ctx_ddl.set_attribute ('logbookTextDS', 'COLUMNS', 'DISC_CMPLNT_TX, MAINT_ACT_TX,LGBK_CMT_TX');

end;

I have created a local partitioned index with the parameter NOPOPULATE create index lb_text_idx on ac_maint (DISC_CMPLNT_TX) indextype is ctxsys.context local parameters ('lexer skipJoinLexer datastore logbookTextDS NOPOPULATE');

When an new value of project_id is inserted into table1 , I create a partition using the following command where prjId is the new value of the project_id ALTER TABLE EVENT split PARTITION pmax AT ('||prjId||') INTO ( PARTITION p_' || prjId || ', PARTITION pmax)

Now I run a huge data load into the EVENT table for a project Id say 1 and insert millions of records.I want to rebuild the lb_text_idx for this partition alone so that data is available for searching by the application. I did a rebuild using the command " alter index lb_text_idx rebuild partition p_1".

However when I run the below sql, I get a count of 0. I know that the text MAINT is definitely present in the table.

SELECT COUNT(1) FROM EVENT WHERE PROJECT_ID = 1 and contains (DISC_CMPLNT_TX, 'MAINT' ) > 0

When I run the below sql select parameters,status from user_ind_partitions where partition_name = 'P_1' , I get parameters as null and status as usable.Am I getting 0 records because the parameters are set to null? How do I rebuild with the same parameters for the specific partition alone.