When you open models, only contours are shown for some objects because of the following:
You have disabled the Hide non-configured objects check box on the Objects page (ARIS > Options, Selection tab, entry Model > General > Objects)
You are using a method filter that excludes objects. These objects are not removed from the models, but are only displayed in outline.
The model has objects that are saved in groups for which you do not have read privileges.
Rather than removing the excluded objects entirely, ARIS displays only their contours so that the overall layout of the models is not damaged.
Also, the assignment icon is not displayed for non-configured objects with models assigned.
Objects that you disabled using the properties dialog behave differently. They are not colored, either, but their names, placed attributes, assignment icons, etc. are displayed.