I too am having USB issues on my Z390, except my scenario is slightly different.  I'm using OS X on it, not Windows.  But I see the same issues, having to unplug/replug, but I have a consistent issue which may help them isolate the problem.
 
I can boot up into OS X, everything works fine, but when I reboot it will fail to boot because it continually hangs on the USB driver loading.  I have two ways I can "fix" it ..  I can move all the USB connections to different ports (almost like there's some weird caching issue in the chipset), OR (this works every time) I just toggle Legacy USB support in the BIOS.  OS X will boot just fine with it set to either setting (Enabled or Disabled), but something about changing that value causes the chipset to fix itself and I can boot into OS X.   However, once I reboot, same problem so I have to go in and toggle again or move all my USB connections.
 
So in essence I can not boot 2 times concurrently into OS X without doing one of the steps above, so something is definitely not right.  I have other 390 chipset motherboards from other manufactures and have no issues with these devices on them, in any port.
 
Nothing complex, I only have a Keyboard and Mouse plugged into my USB.  I've tried the 2.0 and 3.0 ports, doesn't make a difference.

Are we going to get a response from eVGA on this one?  Seems it's been a lingering issue since March.
 

ilukeberry
Mine is rock solid... I have ASUS WiFi AC-56 USB adapter plugged in and it works like charm.. I have to mention I don't use any drivers from evga.com just the drivers that Windows 10 1903 provides via Windows update and it finds all drivers.
 
 

The most "common" problem device seems to be webcams, specifically in this case, Logitech 922 series. Do you have one of those to test? I have like 10 other USB devices plugged in, including my CH Products Combat stick, rudder pedals and pro throttle, as well as a TrackIR v5, RIG USB headphones, STEAM controller and a Logitech PS style controller, and NONE of those have any issues at all.
 
Only the 922 webcam.

Is eVGA even looking into this issue at all?

Dear Veratu,
 
I can confirm that we have forwarded this issues to our PM team in order to look into this further. 

EVGATech_LeeM
Hi everyone, we'll look into this.

 Awesome, Maybe this can help, it was working last night and actually for the past couple of days, but after a cold start today it's back to not working again, Logitech c922x Pro Stream Webcam:
 

I have given up on the AsMedia USB 3.1 Gen2 Type C port, and the Type A port next to it.
 
Constant drop-outs, and while I cannot prove it, I sincerely believe the Type C port burnt up my ADATA XPG SX8200 1TB nvme drive.
 
Fortunately, I found Intel drivers.

Cool GTX

f1ss1on

UPDATE

Finally, after almost a year of going back and forth with Logitech Support, they have been unable to fix the issue. Since I had purchased the 2 C920s versions of the camera, they have agreed to send me 2 new Logitech Brio's. This is definitely an issue between the C920 ONLY. Both Logitech and I have tested numerous models with the Z390 FTW. The only cameras that had failed was the C920.

Thank you for the update & sharing your results after all the testing

Most definitely!