This occurs quite often as if time consuming to work with.
I have quite complex hierarchy of model already in the tool (6 layers deep on multiple paths in number of 10). When I am on some model level and add new Model element, it triggers some action on Model Explorer layout view, the results looks like random organization.
but it closes my currently opened models hierarchy in tree structure and opens others which were closed. It simply produces other hierarchy view then I worked with. its opening randomly some folder and close others…
It definitely just occurred few moments back again on New Model added to hierarchy.