1 Create New Project
2 Add audio file
3 Go to device manager/audio hardware setup
4 change buffer size
5 hit apply/exit out of device manager
6 play audio
Sometimes audio will not play back/meters show nothing
same as in C7-7.5x
must restart Cubase to fix problem.
What happens if you change it within Cubase, via ‘device set-up’?
Probably related to you device driver (which you don’t specify). I change my buffer size all the time even while in playback with no issues (other than the stutter when the audio stream resets.
Hi Doktari
Bad news is, this has always been a feature for as long as I’ve known it. Some hardware doesn’t like changing during a project and needs changing outside of cubase before it starts up. Some hardware configs don’t even let you open the window where this can be changed inside of cubase. On my MOTU Ultralite MKIII the issue is intermittent, ie I might be able to change this and I might not. Once cubase has decided to ignore clicks on the button at the top of the device manager/audio setup page, only coming out of cubase will allow me to change these settings again.
It’s very wrong of me to have got used to this and you are right to expect it to work… but it doesn’t.
However, whilst it’s sometimes very inconvenient, it is not a ‘show stopper’ for me. Hopefully you can learn to live with it without being tempted into buying another card that brings you a whole host of other issues 
Hardware is Steinberg MR816X, when going to the setup inside of Cubase.
Hello,
I’m moving this out of the Issue Reports because it sounds more like a system specific issue, rather than a problem in Cubase. I wasn’t able to reproduce it anyways. If someone can reproduce it every time and has a step by step description, please post it here.
Cheers!
Update or reinstall drivers. My mr816x works like expected.