XML parsing error on generating report

Hello all,

running oracle 19c on linux rhel. in one of the PDB's when trying to run an AMMD report i get the below error.

there are no invalid oracle objects in the PDB, the report runs fine on other PDB's within the same ROOT. the AWR report works

SET LINESIZE 200

SET LONG 1000000

SET PAGESIZE 0

SET LONGCHUNKSIZE 100000 

SELECT DBMS_STATS.report_advisor_task('AUTO_STATS_ADVISOR_TASK') AS REPORT 

FROM  dual; 

ORA-20012: Statistics Advisor: Error generating report details: ORA-31011: XML parsing failed

ORA-06512: at "SYS.DBMS_STATS_ADVISOR", line 3571

ORA-06512: at "SYS.DBMS_STATS_ADVISOR", line 891

ORA-06512: at "SYS.DBMS_STATS_ADVISOR", line 5377