Weird issue on my 2015 15" MBP: When I insert my USB 3.0 UHS-II SD card reader slowly, it is recognized as USB 2.0 speed. If you insert it quickly it is recognized as USB 3.0 speed. This is confirmed in Blackmagic Disk Speed Test using a Sandisk Extreme Pro 300MB/s SD card and a Sony UHS-II SD card reader. I think what's happening is the Mac is seeing the first set of pins when you insert it slowly (not abnormally slow—the issue actually happens frequently) and thinks that it's only USB 2.0. When you insert it quickly all the pins make contact (including the back ones) before the Mac has time to react and it sees it as USB 3.0. Does this happen to anyone else and if so, is there something wrong with this machine? It's a work computer that I received a couple months ago when switching jobs. Or could it be something wrong with this card reader? I'm leaning towards that since I don't seem to have the same problem with my Samsung T5 2TB external SSD. Either way it seems like a strange glitch.