No error is shown. After discovery completes for a source folder containing PST files, go to Sources & Pre-Processing tab and then expand the Case Folder and subfolders. Custodians are not automatically being assigned to the PST email files. Here is a screenshot from a Veritas internal lab showing the issue:

When working properly would look like the following:

There were code changes to eDP v10.2 that caused this issue.
A hotfix is available for this issue in the current version(s) of the product(s) mentioned. Contact support for the patch if requiring a fix for eDiscovey Platform v10.2.
This issue has been resolved in eDiscovery Platform v10.2.1.