Been around the block a few times since I last posted. My USB 3.0 (Lexar) external card reader works on my laptop with Win10 on a USB 2.0 port. I took the reader, along with the rig, into a shop after beating my head against a wall for months. Mobo is an older ASUS P6X58D-E which did pass the Win10 compatibility test, but ASUS is not issuing Win10 drivers. The drivers in question, however, are standard USB drivers, not mobo or card reader specific ones.
The shop's report is that there is a weird behavior on some machines that upgraded from 7 to 10, and sometimes, but more rarely, appears in clean install 10 situations. It appears that 10 reinstalls what it considers the correct driver (even though it isn't) on each boot, replacing any driver that is not MS signed or that it doesn't like. There is supposedly a MS tool that prevents this mindless activity on specific drivers, but it didn't work on my rig.
There is simply no apparent fix for this unless and until MS decides to fix it. And who knows where this bug is on their long long list of bugs to fix.
This philosophy of theirs, total control by MS, over my machine is getting really old. I am beyond the point of being able to roll back to 7 without a complete new install of 7, with a new license.
What I'm going to do for now is to put the CF card into my external reader, attach it to my laptop and copy the files to a flash drive and use sneaker-net to move the files to my main LR computer. I could, and have done, attach my camera directly to my LR rig. At least 10 recognizes it as a drive. This makes it somewhat easier that the foregoing, but it does tend to drain camera battery life.
I will put my faith in faith in M$ for now... That's a lie. I have no faith in M$ to listen to any consumer (they are putting the higher components of 10 on a subscription basis, and they are changing their 7 updates to the same rigid cumulative update policy that they use for 10). I'll just fake it until it becomes an overwhelming problem and then decide something.
