did you press the bake button in dynamic paint settings?
(edit) btw I couldn’t get your file download to work. try pasteall or use the attachment feature.
I know this thread is some older… am having same issue… brush is set to Proximity and have baked all dynamics… nothing
my brush (cute) will not paint on the canvas (plane)
Ok, I am struggling with Dynamic paint and cycles too.
Using the most basic setup, a subdiv plane and a cube to paint on as the brush.
Set the plane as the canvas and the cube as the brush, shows correctly in the viewport, but on rendering in cycles, nothing happens.
Simple to do in Blender Render, so presumable cycles has some hidden setup needed?