ORA-20006: cannot gather session private statistics for <TABLE_NAME> without truncating the table

Oracle 12.1.0.2 SE on Linux (AWS RDS Instance)

Hi,

I currently have an issue when trying to gather privates session stats on global temporary tables. The problem is intermittent and seems to happen when the GTT reaches a certain size. My GTT was created as a transaction level table (on commit delete rows) and stats set to SESSION (not shared). I can gather stats with no problem if the table is less than 22K rows (for example) but as soon as I hit 22K rows, I get the below error when gathering session stats. Is this a bug?

--<INSERT_STATEMENT>21,999 rows inserted.exec dbms_stats.gather_table_stats(USER, 'TABLE_NAME' );PL/SQL procedure successfully completed.--<INSERT_STATEMENT>1 rows inserted.exec dbms_stats.gather_table_stats(USER, 'TABLE_NAME' );ORA-20006: cannot gather session private statistics for <TABLE_NAME> without truncating the table