problems accessing an index when using a variable inlist

I am using the standard variable inlist code from asktom. I find that when I use it, I cannot access an index. The query performs fine when the inlist is hard coded or when I first insert to a global temp table and select from the global temp table.

I checked to make sure the data types were a match. My my type is a varchar2(4000) and the underlying column is a varchar2. Here is my where clause.

  FROM tab1 a LEFT OUTER JOIN tab2 b ON (a.col1 =b.col2)

                    LEFT OUTER JOIN tab3 c ON (a.tab1 = c.tab3)
   WHERE a.col1 IN (select * from table( select cast( k_utility.func_varchar_in_list(col1) as
                              t_varchar_tab ) from dual a))
     AND  a.datefield> (SYSDATE - 10);

as I said Oracle uses the correct index when I hard code the values or if i use the k_utility package and insert the records to a GTT and then query the GTT.

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