According to a licensee, StageFiles() is called with ExcludeWildcard that contains a directory name ("Engine/*") and bRecursive=true when building DLC. This is not supported by Directory.GetFiles(). Licensee suggested a fix which will however not handle the issue in a generic case.
See https://udn.unrealengine.com/questions/269457/pattern-parameter-issue-in-directorygetfiles.html for details.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-24541 in the post.
| 0 | 
| Component | UE - Foundation - Cpp Tools - Automation Tool | 
|---|---|
| Affects Versions | 4.9 | 
| Created | Dec 16, 2015 | 
|---|---|
| Resolved | Apr 19, 2019 | 
| Updated | Mar 26, 2020 |