i have been using my UR22c for a loooooongggg time, and have loved it, recently i have changed pc and have been using it fine on the new pc up until now, the (MIX) knob now doesn’t work, i love being able to hear myself when playing games, now i can’t, if i put it completely to (INPUT), i hear everything, if i put it completely to (DAW) i hear everything, it just doesn’t work… full stop 
i noticed it had stopped the moment i tried downloading dspMixFx v3, i couldn’t work out where to find loopback, so i uninstalled it and returned to v2 where i knew my way around, now i cant find my way back to hearing my self, everything is the EXACT way it was setup for the entire time, Mic connected to input 1, full gain, so that isn’t the issue, headset output volume is max, so that isn’t either, what have i done wrong? note i have been using it fine on the new pc until i downloaded and uninstalled dspMixFx v3
The mix knob is not working for me either after the update.
Hi! I encountered the same issue and even took it to a service center. They said everything was fine and that the problem was software-related. It turned out to be true: I had lent my card to a friend for recording a podcast, and he installed different drivers on it, after which my mixer stopped working.
In the end, I downgraded the dsp-mix-fx version, the driver version, and the TOOLS version, and everything started working as before. You can find the latest old versions that will work with your card on the Steinberg website. (The service center mentioned that there’s information about this on the site, but I couldn’t find it…)
Which version is the working one?
I’m not religious but thank the lord! Finally found someone having the same issue! So go back to previous release driver, software etc and it’s back to normal then?
Will give it a go and report back, have spent 2 evenings on this so far, very close to destroying everything within a 2m radius of my chair with my guitar 
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Didn’t go backwards but forwards. Went onto the downloads page and found a newer version. I don’t like going backwards so I hit the buttons and upgraded.
And aht do you know, IT’S BACK!
Been working on a TOOL tone with multiple amps and heard it straight away, my hearing sucks so don’t know how close I am but instantly reminiscent of Stinkfist so pretty happy camper.
-1 Steinberg for breaking it
+1 Steinberg for fixing it
Forgot to add a tip sorry. For Windows at least (burn in hell apple 
)
Unplug your magic box before you start your computer up and leave unplugged until your finished. I made this mistake on the 1st go and even though I ended the processes it mentioned to stop I still couldn’t get it over the line.
Was there any fix for this? I am on the latest version
Hello everyone I came across this topic with the problem that the mix pen doesn’t work, I found the reason that worked for me! In the upper right corner of the mix dsp, there is a switch between Stream Mixer and normal modes. There is also a headphone icon, in short, the headphone icon is green. You need to activate it in the first normal mode, which is “not a streamer mixer” and then switch to the streamer mixer mode and adjust all the levels there, and then the mix knob will work as expected.