System Information
Operating system: OSX High Sierra
Graphics card: AMD Radeon R9 M370X 2 GB / Intel Iris Pro 1536 MB

Blender Version
2.83 Alpha
Date 2020-03-12 19:47
Hash: fa823f0af867

Short description of error
If there are 2 GP objects in the scene and one is set so that the Stroke Depth Orientation is 2D Layers and the Other is 3D location, there are odd graphical glitches

Exact steps for others to reproduce the error{F8402918}

1. Start a General scene.
2. delete cube
3. Add GP Monkey
4. Move Monkey slightly forward in Y space.
5. Add a GP Blank
6. Create a layer and material with a fill colour selected
7. Go into draw mode
8. Draw a large shape behind monkey.
9. Go to Object mode
10. Set the shape GP object to use £D Location as Stroke Depth Order
11. Rotate camera around and you will see glitches.

Glitches look like random shapes that mask the monkey and glitch in other ways.