For initial concept models, with changes in parts (not only in shape, but whether they are there or not) happening constantly, I have evolved over the years to an odd workflow. I have a single concept part file. As its elements take shape, or are deleted, or emerge anew, I manage them in configurations utilizing Body Delete (or Keep) features. In this way, the entire pseudo-assembly emerges, without having to manage individual transient part files -- most of which will have never been brought forward. A sand-box part, if you will.
These configs are brought into an assembly, which can move the pieces and confirm the kinematics. And it is at that higher (actual assembly) level that I am experiencing a problem I haven't seen before.
When bringing in different configs of the same part into an assembly, certain part-level sketches are always on in the assembly. I need certain controlling sketches visible, and to control their visibility on a per-part basis. This is why I have the configs set to have individual appearance control.
However, in this latest SW version (I have 2018 SP5.0), certain sketches always reappear in the assembly. I've tried going to the offending part, moving thru each config and saving it then. I've tried saving-all, multiple times, at the assembly and part level. Certain sketches keep showing up; and I don't have them visible in ANY config!
Specifically, I open the assembly (containing various configs of the same part file), and there are no sketches seen -- but some parts are lightweight. When I edit one config, or "set all parts to resolved," the problem sketches become visible. And they've been doing so no matter what I've tried.
This isn't a new workflow for me, but it is a new problem for me, and I can't make it go away.