So, let's say I have a shape and I use the shape/path stroke. I set it to 5 and there's a stroke now. Cool. I modify some things in the shape path and the stroke disappears. If I set the stroke level higher or smaller it comes up again but if I set it to normal again (5) it disappears again.
This problem is really annoying.
Here is before I modify the shape:
And after:
you can see I didn't change anything in the stroke panel
This sounds like a problem with your local set up of Illustrator.
Visual inconsistencies can be caused by several factors, all of which you should check to see if they solve the problem.
Restart your computer - Visual inconsistencies can happen if the available memory on your computer dips below certain thresholds. If you restart your computer (clears the memory), and notice that the issue subsides for any period of time, this is most likely the culprit.
Graphic Card - You may have an outdated driver for your graphics card, or your card may have low visual memory. Check the specs of your card against the most current drivers and also against the min. requirements for Illustrator. Often times, even if your specs meet the minimum, having large files or multiple CC products open at the same time can cripple your experience.
Illustrator Settings - There is a small chance that the issue is with your local set up of Illustrator itself. One option is to switch between GPU and CPU rendering as this support ticket outlines (https://forums.adobe.com/thread/2011349) to see if there are any changes. Tweaking your visual settings may correct this problem.
Try these solutions out and see if there is any change whatsoever. The root of visual inconsistencies is often a personal, local issue so a universal answer to this question isn't possible.
