I have an HP laptop (model Spectre x360 15-BL012DX) that has 2 thunderbolt 3 USB-C ports. I've noticed 2 different, but likely related, odd behaviors when I connect HDs to these ports. I'm wondering if anyone has any thoughts as to what cause these symptoms as I'm simply coming up empty.

I should first note that the HDs that I am attaching are USB 3 2.5" drives that can be powered from a USB port. The drives have cables with standard USB 3 connectors and so I have to adapt these to work with a USB-C port.

Symptom #1: If I connect a HD using a short 6 inch USB-C to USB Type A adapter dongle, then the HD is not always seen by Windows. Windows detects that something was connected but File Explorer will sit there for a long time trying to refresh without ever showing me the newly connected HD. Other times it connects just fine.

If I now take a USB hub that plugs into the USB-C connector and plug the HD into one of the USB 3 Type A ports on the hub, the HD will work flawlessly. This is true whether or not I plug the hub into external power or not so this at least proves that the port on its own can supply enough power to the HD.

Symptom #2: Once again, I plug a HD into the USB-C port using the dongle. Let's assume that this time the HD is seen just fine and I can access the drive with no problem. When I am done using the drive, I use "Safely remove hardware and eject media" to disconnect the drive from my system. However, I find that the drive WILL ALWAYS reported as being in use and the utility will fail to eject the drive.

If I connect a HD using a hub, the drive can be successfully ejected every time.

Note that I have tried to use multiple different USB-C to USB 3 Type A dongles from various manufacturers, but the results are always the the same.

Summary: When connecting a USB 3 drive to a USB-C port using a USB-C to USB Type A adapter, I have problems. However, if I connect using a HUB, it works flawlessly. Does anyone have any ideas on why this may occur?

Test scenario is using the HP notebook listed above with Windows 10 1909 including the latest Feb 2020 updates.