NJ 10 fails on high DPV1 Read/Write load

NJ 10-DPS is configured at 12 Mbit/s by config.nxd (tested with 64 and 1 byte I/O size).
Application reads and writes IO data.
Master sends DPV1 Read and Write requests as fast as possible. Application sends responds.
netX CPU load is about 90 %.

After few seconds firmware stops cyclic communication and reports communication error TLR_E_PROFIBUS_FSPMS_ALARM_HANDLER_PENDING (0xC0090024).
Task PROFIBUS_FSPMS reports error 0xC000000F.

Note: Application did not send any Alarm during the test.

After Channel Init RUN flag is cleared, communication error stays unchanged.
After System Start communication is possible again.