SSD and various usb interfaces

[Gorlash]

This is probably more of a usb question than SSD, but I'll start here...

So I have a new x570 motherboard, which has 'USB 3.2 Gen 1' and 'USB 3.2 Gen 2' outputs...

I have a Maiwo Type-C 3.1 Gen 2 to M.2 external device, with a 512GB M.2 drive in it.
I got a USB Type-C to Type-A 3.1 Gen 1 Cable from Amazon, to connect this device to my computer.

I'm using HD_speed V1.7.2.91 on Windows 10 Pro to test the drive.

When I connected the drive to the USB 3.2 Gen 2 output, I got almost 1GB/second throughput, but after about 10 seconds the program just hung; I had to unplug the device to free up the connection.

When I connected it to the USB 3.2 Gen 1 output, it ran reliably, but I only got about 470MB/second throughput, which is about SATA speeds; not what I expect from an M.2 drive.

So what is going on here?? Why would I have a problem with the 3.2 Gen 2 output? Even though the cable is only USB 3.1, shouldn't the interface be backward-compatible??

More generally, which component should I look at when trying to decipher this issue?