We also experience same issue, we solved by doing this :

1. Shutdown all pega instance

2. Take a database backup, in particularly at tables as mentioned in point 3.

3. Execute scripts below :

delete from pegadata.pc_work_dsm_batch where pyid = 'pzStandardProcessor';

delete from pegadata.pr_data_decision_ddf_run_opts where pyworkobjectid = 'pzStandardProcessor';

delete from pegadata.pr_data_decision_df_part where pxworkid = 'pzStandardProcessor';

delete from pegadata.pr_data_decision_ddf_error where pxworkid = 'pzStandardProcessor';

delete from pegadata.pr_data_decision_df_met where pxworkid = 'pzStandardProcessor';

delete from pegadata.pr_log_dataflow_events where pyrunid = 'pzStandardProcessor';

delete from pegadata.pr_data_decision_ddf_runtime where pyrunid = 'pzStandardProcessor';

delete from pegadata.pr_data_qp_run_partition where pxqueueprocessorname = 'pzStandardProcessor';

commit;

4. Startup your pega instance.

Hope it works.