R12.1.3 : Patch 18120913 fails with "FAILED: file icxblknt.wft on worker x"

Hi

I am attempting to apply patch 18120913.

My patch procedure was as follows;

1) apply 18120913
- patch fails with
  FAILED: file icxblknt.wft on worker x.
  FAILED: file POSSPAPM.wft on worker y.
 
2) Apply fix: Patch 18273727
"Patch 18120913 Fails with ATTENTION: All Workers Either Have Failed Or Are Waiting (Doc ID 1674893.1)"

3) Reapply 18120913
- patch still fails with
  FAILED: file icxblknt.wft on worker x.
(NOTE: POSSPAPM.wft no longer fails)
 
4) Worker log file contains this message;
ACTIVITwferr:
  - 1602: Could not save.
  - 1400: Could not save to database. MODE=UPGRADE EFFDATE=<null>
  - 1404: Please first load this entity or check protect and custom level of PROCESS_ACTIVITY 'WFSTD/FED_BUILD_PA_AP_INVO_ACCT_GEN'.