Addendum: This is an issue with German language only. Indexing with all other languages work as expected given there is enough RAM available to the JVM (sometimes the error messages issued are somewhat strange when they report negative array indexes in case of insufficient memory).

Meanwhile I found two other packages exhibiting the same problem.

The Java Batch runs on a Windows 8 Box with Base 8.1.1 and Java 1.8.0_40_b25 installed in client-server mode.