So, this is a little complicated but I'll try to be as clear as I can.
Let me start by saying I've been using SolidWorks 2010 and 2012 for six years or so now. The marketing department really loves the renderings I've been able to produce for them using PhotoView 360 in 2012. I've recently updated to 2018 and I'm working on my second rendering for them.
I modeled the filter vessel with great detail and the over all assembly has 5 sub-assemblies and one stand alone part. In order to display the internal components I usually do a cut out at the assembly level of the vessel shell. In this case, it is a vertical vessel with a flat closure on the top.
The first cut out I did was a 2D spline drawn on the Front Plane which went from near the bottom of the vessel all the way up through the top closure. In the feature definition, I specified, what I thought was, only the shell and the closure to be included in the cut. Turns out, I accidentally selected some components of the filters inside as well. On discovering this, I went back to the feature definition and removed the unwanted components from the item selection box and closed it. With the items removed, they are still showing as part of the cut. I have since deleted the cut and sketch all together, saved, and reopened the assembly and created two new sketches and cut and still the components of the filters are being cut from the original extruded cut.
More over, when I suppress the current cuts, the cut in the closure shows suppressed, but the components still visually show the cuts. I have double checked the sub-assemblies and I did not propagate the cut to the components. If I suppress and unsuppress the components they show normally until I start the rendering. Then everything goes back to the original sketch and cut and I can't make it go away.