dspMixFx: can't open even after Cubase 9.5/10 closes

After running Cubase 9.5 or 10 using the UR-RT2, I cannot access the device using dspMixFx. It says “Cannot use USB port; it is being used by another application.” And I have to reboot.

i have to say that while I like what I’m hearing from this interface, esp. with the Neve transformers on vocals, the extremely poor quality of the software is giving me pause about keeping it. It is buggy and cumbersome, to the point of actually being in the way, rather than helping me track. And the aesthetics are horrible - does not connotate “high-end audio equipment” but rather “very bad 1990’s web site.”