We have not see this behavior. If you are still seeing these issues, can you share the following information :
1. iOS device
2. OS info
3. Do these issues happen all the time or are there any specifics steps to introduce the issues?
1. iPad 4 non jailbroken,
2. OS 8.1.3
3. It happens all the time with Adobe Draw (Adobe line it's ok). It doesn't need a trigger: when you create a new project with its 5 drawing slots, you can see that the BG is on a light grey instead of white, and when you erase someting on a superior layer, you erase this light grey BG revealing an opaque white BG, that deny you from seeing the layers below
an image with 2 layers, being letters above and traces bellow
ANd the same image with the letter being erased
AS you can see, erasing the upper layer creates something as a white mask.
Based on the images, seems like you are applying one of the tools with white color, instead of using the eraser. Please try the following:
Tap on the "Tool Selection" icon
Now the tool bar changes to different tools available, please select the Eraser tool and to do erasing as needed
Hope this helps,
oh my... You're completely right... My fault
AS i'm not so used with Draw as I was with Ideas, I've selected the wrong tool.