Update All Indexes and Tables results in Writer hangup

I had a writer document which contains a Table of Contents and an Alphabetical Index. This was working before. Now when I go to Tools - Update - All Indexes and Tables the writer never ends. One processor is 100% busy with soffice.bin (LINUX). Only solution is to kill soffice.bin and restart with recovery.

If I only update the Table of Contents, it works. Any update on the Alphabetical Index results in the hangup loop.

Any hints what I can do or should I open e bug?

Regards Rainer