(I'm on Unity 2019.4.10f1)
Not sure if this bug has been caused by me upgrading Unity or by something I did in my project, BUT -
1) When I create a new doodle, it's all good! Until I hit save, and look at it in the inspector. When I do that, the top 2 quadrants and the bottom right quadrant are completely grey. :( When I bring it into the scene, the problem persists.
2) When I go to edit an older doodle from before the bug happened, as soon as I click "edit" and the drawing window appears, suddenly the top 2 quadrants and the bottom right quadrant are completely grey in every frame of my doodle. :( It also appears that it's not a solid grey but a semi-transparent grey.
3) I have not noticed any errors appearing in the console indicating something is wrong.
Just wanted to bring this the developer's attention, and if anyone else has experienced this and has some workarounds, I'd love to hear them!