If so, you have to report the information to your reseller so that he can report the bug to SolidWorks.
@gt22: editing a part allows you to make the modification from the assembly and in particular to be able to attach to another part of the assembly and isolating allows you to keep on the screen only the "n" parts concerned rather than viewing the whole machine. So I find the approach very logical, right?
It doesn't seem to be a simple bug because when I check again, I have the opposite problem of @tsimard: when I edit an isolated part, it is necessarily opaque and I can't make it transparent.