I used to use them regularly...now when it rains, for fear of losing a blood trail, I usually exit the woods.
I've also noticed from other's that deer seem to notice them more in our area than in the past...and not seem to mind a man in a stand, but get hinky if there is the umbrella up...
Most will have some motion to the material if it's breezy..maybe that's the issue?
I used a Magnum Porta Roof... there were 2 attachment styles...one had a screw in piece to mount the umbrella and the other a strap around the tree... legally, we need to use the strap type in PA on public land, but....