This occurs with a large canvas:

On tapping an "eye" in the layers panel, there is no immediate feedback. The "eye" is a small target for a tap. I find myself thinking I've missed the active area, so I tap again. Several seconds later, the visibility of the layer flips to what I wanted, and back again.

This is due to the absence, in the "control", of immediate, positive feedback that the tap hit within the active area.

The feedback could be added with a little sparkle, starburst, really, anything. Then I'll have the patience to wait for Artrage to flip the visibility of the layer.