Operating system: Windows 10
Graphics card: did a test with both GeForce 560Ti & Nvidia Titan XP
Short description of error
I got some artifacts on my grease pencil strokes, in the viewport and in the renders (eevee or workbench): https://i.stack.imgur.com/TRtij.jpg
Seems that it happens only on certain layers an not on the others.
Note that they already have a different Z position.
It seems that moving one of the GP layers slightly makes it work, but anyway, that's weird (see video here : https://imgur.com/a/tfsjzSJ)