Problem with Jobs; Can't edit finish date

Hi Forum,

Server: 2014.0.2 (120664)
Client: 2014.0.2 (120664)

one account can't edit the finish date of existing jobs.
Following steps are performed:
- In the jobs view double click a job and set a new finish date, save.
- windows closes and in the job list the new date is visible.
- click on another job and the date of the edited job resets to the original finish date

This is reproducible with any job, whether it is a new one or existing. It's the same in caching and online mode. Also after I've done any gwcheck I'm aware of (structure (online and caching), content (online and caching), reset client options)...

Interesting fact: If jobs are edited in the quick view window the new date will be persistent. Unfortunately even if the new date is correctly visible, the job alarm pops up at original date. In the client and also on the phone the old date will be alarmed...

Any suggestions what to do and how to fix this?

Thanks in advance,