ESTK workspace not persistent anymore

Dear friends,

Since a while - propably an FM update - the selected workspace (DDD) is lost after closing ESTK CC (4.0.0.1, ES 4.5.5, ScriptUI 6.2.2).

At the next open of ESTK the selected workspace is briefly visible, but falls back into the Empty workspace, although in the dow-down-list it is selected. I need to reselect it.

I have checked the preferences - but can not find an appropriate setting.

Klaus