[Performance] Cannot draw on an existing frame

I have multiple layers, each with multiple frames. When I try to draw or erase on a frame that already exists for any of the layers, Fresco says "Cannot draw (erase) on a hidden layer", unless it's the first frame of the layer. I can, however, draw or erase if I create a new frame for the same layer. I am using pixel layers and pixel brushes. I'm not sure if this is a bug or I'm doing something wrong. 

[Renamed by Mod]