Virtualbox 5.2.X usb 3.0 device passthrough issue xHCI

As a side note. A friend had issues with passthrough on an older instance of virtualbox (5.2.18). He was using the XHCI extension for USB 3.0 passthrough (proxy). Dual passthrough devices existed in the virtual host, and intermittent (read, non working) connections.. Reverting back to the USB 2.0 extension seems to work better.