Shape or outline's bug ?

[Kaï]

Hi,
I don't know how to clearly explain my issu… let's try 🙂
I drew a simple shape but, on the corners, there's a kind of bug… or is it me who forgot doing something (20 years I use Illustrator and it's the first time I see that !) ?
As you see in the attached screenshots, It's like I had an outline however I haven't even applied one.
Does anyone have an advise ? someone can help me please ? 🙂 
I hope I was clear enough…
Thank you.

[Monika Gause]

Does it vanish in View > Preview on CPU?

[Kaï]

Hi Monika
Thank you for your answer.
It's better indeed :

But is it normal that I can't zoom in more than 780% ? is it the limit of CPU's preview ?

[Kaï]

It's ok, it works.
I restarted Illustrator and now I can Zoom in a lot more than 780%.
I still find weird that we have to enable "preview on CPU" for a so simple shape.

Thank you Monika !

[Monika Gause]

Preview on GPU ( your graphic card processor) is fast, but not precise. You can try if your graphic card driver can get an update.

[Kaï]

Thank you !