Error in USER-DEFINED parameter Handling

If I change the "Parameter Group" to "USER DEFINED" in a description file on the master under "Parameter Configuration", add new parameters, then change the "Parameter Group" back to "ALL" and select the "EDS Default Values" button, the USER DEFINED parameters are not removed. Furthermore, I cannot delete the USER DEFINED parameters. If I change the view to a certain parameter group, e.g. Slot1 and then back to ALL, I won't see any parameter at all. Only when I close the complete configuration and open it again, the parameters are displayed again.
Then I can also cut the USER DEFINED parameters again, but the button "EDS Default Values" still doesn't work.