Whenever I use a toolbox component, such as lengths of aluminum angle, errors happen when I reopen the assembly later. The pieces of aluminum angle will open without any holes or cutouts and that messes up mates and sketches on other parts. However, if I open each piece of angle separately first and then open the assembly it is fine. What is causing this issue? I tried "pack and go" to a new assembly to try to break any references outside of the assembly, but that did not work. The answer is probably simple, but I can't figure it out.