Artifacts cannot be found using the Search function

Numerous artifacts cannot be found using the Search function.
The repository concerned has permissions for user guest as Repository Observer, meaning anonymous access is allowed.
The artifacts can be found using the Browse function and using WebDAV.
The problem persists since Archiva 1.2.0.

The following effort has been untertaken to solve the problem:
1. deleting repo/.index and repo/.indexer
2. touching all files and dirs in repo recursively
3. running the repo scan
4. waiting some hours to finish the procedure

After this process, the artifacts still cannot be found. The index-database has the following sizes:
6.1M /opt/managed_repos/internal/.index
8.7M /opt/managed_repos/internal/.indexer

Example:
search for "xmlbeans"
result: 2 artifacts containing "xmlbeans" in the package name, but NOT the artifact whose artifactId is xmlbeans

The Total File Count of the repo is 129542.

Since the search-function is the most important function on the web-UI, we'd consider this a major blocker.