You're wrong and your suggestions are not helpful,
The USB connection is fine because audio (including asio) amd midi are working excellent on the same usb port with drvers in l6Stadium.inf.
The culprir is the Line 6 WinUsb driver (v1.0.0.11 from the installer) and the device hardware/firmware. All other variables have been excluded by me.
The Bulk Transfer interface of the device (hardware ID: USB\VID_0E41&PID_4841&MI_06) always receives the error code 1 with the message "The installation class is not present or invalid". This is a specific error in the Windows device stack that suggests that the driver does not correctly set the necessary registry entries (possibly the ClassGUID or entries in the CoInstallers section) for this particular interface.
The common denominator in all tests is the Line 6 WinUsb driver (v1.0.0.11 from the installer) and the device hardware/firmware. All other variables have been excluded.
Your suggestions are helpful for general USB problems, but do not affect this specific Code 1 installation error of a single interface.
So don't take me for a fool.
Best regards