There is most definitely current in Erie, speed probes prove that. Also the fact that the lorain sandbar exists is also proof how do you think it was formed? I don't believe currents exist ALL over the lake but area's like Pt Pelee, Avon Point, around the islands, MI waters near Maumee River, Detroit River, Lorain Sandbar, and out deep in the central and eastern basin there is current without a doubt.
The areas you are diving it may not be conducive of solid tests, plus current may not be on the bottom it maybe in the middle of the water column which is probably more than likely the case and with you being a human probably weighing 150 or more how would you feel the current, the currents we see on our speed probes are a difference of .2-.5 mph a heavy dive rope wouldn't move at times especially if only a small portion of the water column has current. The currents are subtle but they are there.
The surface currents are crazy, last week I was off Avon I was trolling 2.4 mph I turned my boat and was going 1.0 and didn't even touch my terrova or kicker motor, my motor even made an audible change in sound.
Does't even make me wonder I've been watching this map the currents off Avon are extremely strong.
http://www.glerl.noaa.gov/res/glcfs/currents/
Fish follow these current. (I know I'm referring to surface here) but fishing the area and lorain I know by trolling direction sub currents exist as well.