UPDATE:
After downloading and debugging the CrashReporter, I was able to narrow down the issue. The CrashReporter itself is not the problem and works correctly.
However, the crash files within the Windows Error Reporting (WER) folder are incomplete. It seems that UE4 (or Windows?) should write dumps (*.log, *.xml, *.dmp) to the folder C:\ProgramData\Microsoft\Windows\WER\ReportQueue. Afterwards, the CrashRepoter looks through the files and generates the report.
On my machines, the crash report files are not written. There exist the correct subfolders within the ReportQueue directory, but they only contain a single Report.wer file. There are no xml files, and so the CrashReporter can’t do it’s job.
Who is writing these files? UE4 or Windows? Any idea why they are not present?