I did some research but could not find the answer. I made a masterplan with some subplans in it (a projectplan with inserted projects).One of those subprojects is changing his end date by itself. When opening (collapsing) the plan it switch immediately to the right end date. Which, in my opinion, is weird. I searched what could go ‘wrong’ in te subproject but could’t find any.
Depending on how you set up the Master Shell, you may have inadvertently used a "new" file with a start date in the future, compared to the subprojects; You then may have linked a task wing the Master Shell which caused the end-date to shift to the right.
Make certain the calendars match in the projects. If the master uses a standard (default) calendar and so do the subprojects, then also verify the standard calendar has not been modified in the subproject files.
A common error is to modify the standard calendar with company holidays, etc.