I did a swap of single parts for assemblies with some very weird SW behavior (see https://forum.solidworks.com/thread/53677) and now I'm afraid that SW is terminal. I had a plane defined by two axis through bottles. Now when I select that plane (which clearly goes through the parts) it doesn't draw the plane, and when I select section it says it doesn't go through the assembly which is impossible as it is defined by the centerline axis of two adjacent bottles in the assembly. I tried deleting the axis selections and reassigning them and nothing. I tried deleting the plane feature, selecting rebuild, and defining a new plane using the centerline axes and it neither displays the plane during the definition nor will it display the plane when planes are selected and still says the plane doesn't intersect the assembly. Does SW re-write it's software as it seems to forget how to do more things the longer I use it. Exiting the program and starting over doesn't work. Selecting different axes in the assembly doesn't work.
It obviously has set something wrong during it's self file corruption process, but of course gives no indication there is a problem let alone what it might "think" is wrong.