Workflow Directory Services User / Role Validation requests fail with error

Hello,

We're on EBS 12.1.3.

On a recently refreshed test environment we've got a workflow issue and after doing a bit of research I thought I should try and run "Workflow Directory Services User / Role Validation".

I first ran it with the following parameters:

Default Batchsize=10000
Fix Dangling User/Roles=Yes
Add Missing User/Role Assignments=No

Then with the following parameters:

Default Batchsize=10000
Fix Dangling User/Roles=No
Add Missing User/Role Assignments=Yes

On both runs, all of the resulting "WF_LOCAL_USER_ROLES (Check Event Alert)" concurrent requests complete with error. There's nothing in the log and no output. The diagnostics screen says: