Stroke and fill errors (Outline and irregular fill)

Hello community.

I need some help understanding 2 errors that are bothering me intensely.

(video provided)

Problem 1:

When creating a shape with sharp corners and you zoom in, there is an added thick stroke that appears. When converted to outlines there's nothing there and there are not many points in question - and the points are all correctly set up. I know it's a tiny detail that normally can't be seen unless zoomed in a lot, but imagine having a logo or design printed in large size, then it could be very noticable.

When saved it saves with the stroke as a part of the image and the only way I and my colleagues found to fix this stroke problem is to create random points here and there close to the corner, which I rather not do.

Problem 2:

When working with filled shapes, the fill doesn't appear in the entire shape and is irregular which can be a problem when creating very precise work, as I can't see the final look until I export the file. This is highly annoying and I would love a solution for this. 

This happens randomly and in all shapes, simple and complex. Even on a simple circle - 

This is a recurrent error in all my files but only started recently (2 months)

• Is this a bug after the latest updates?
• Is it my graphic card acting up? Is it some kind of settings that have gotten messed up?
• What could it be?

Please, help me save my sanity as we feel we've tried everything.