Can you show me a screenshot of "VT-x" showing as inactive?
The FEL mode chip is showing up fine - yes its that Onda tablet thing - they are the earliest users of the SoC thats on the CHIP, so their name got associated with the particular usb id used by the SoC in FEL mode.
The only thing I see amiss is that in the usb settings of the VM, I don't see the Onda tablet being actually connected to the VM. If you re-run the VM, and manually "enable" the Onda device connection to it, does that make the flasher VM see it?
Other than that - see if completely uninstalling Virtualbox and reinstalling makes a difference. The filters and everything are all already correctly configured on the OVA, so you should not need to mess with those. Another thing to try is running Virtualbox as administrator.
Failing all this, see if you can snag a live-usb linux image to boot off a usb stick, and try to use that.
Edit: this "check mark" next to the Onda device is missing: