adding asset(s) to project causes "open behavior library" button to move out of window

Adding an asset to project causes the toolbar with the asset library buttons to move right, causing the rightmost button (open behavior library) to move half-way out of the window. only way to  get this back seems to be to maximize/normalize the window. see attached screenshots.

happens when adding asset via different means, library buttons, file menu, add asset button. happens when maximized/normalized window, fixes itself if maximize/normalize from current window state. happens with any asset type, file name, etc.

Only happens on Windows, OSX does not seem to have this issue.