Are you using really low output pickups?
So I have one guitar that doesn’t love the QC tuner but I think it’s an issue with the guitar. It’s an incredibly resonant guitar and it’s a Strat and I think the tuner gets confused or picks up some of the spring noise from the trem. Does way better if I deck it or if I pad the springs or use a string dampener (gruv gear on headstock above the nut). All my other guitars tune fine on the QC
Could this be your problem? What guitar are you using?
My experience (I own kemper and Quad cortex) makes me prefer the kemper tuner so much! The kemper has an excellent tuner and very fast in reading the string… with the Quad cortex unfortunately it is as if it unhooks and the ball jumps abnormally… really unbearable for a professional device!!
Huh…interesting. This is the first I’ve heard of QC tuner problems. I’ve never had a problem with mine…quick and accurate. Any chance that a device upstream might be introducing noise and causing the tuner to mistrack? I don’t mean to be insulting but, no active chorus or flanger pedals ahead of the QC, right?
yes! something is wrong with the tuner. I use different tuners and QC is not good. always starts high pitched and I have to wait until reaches the actual frequency. I know guitars act a little like that but thos is not that
Hi thanks for your opinion about it! No I don’t use chorus or flanger pedals before entering the Quad cortex… it’s really strange that some don’t have problems with the tuner and others do! Have you installed the latest operating system?
For me its the low E string going way sharp at first and staying longer then the other strings. It makes me wonder if I actually have the low E in tune or not. I don’t notice this behavior to be as extreme on other tuners like my Peterson strobe or my Fractal gear. The Fractal tuner is awesome to me but I prefer the Quad for my rig.
I figured you knew better, Fb, but I did run into that once at a music store where I used to work. The kid swore that his new tuner pedal was defective yet it always worked fine in the store. 
He thought I was making it up when I recommended he put the tuner before the chorus, or shut the chorus off.
Yes’ I updated last week but haven’t noticed a difference in the tuner. You think your tuner woes might be related to the update?
Start using your ears instead! D
I used the Sonic Research Turbo Tuners for years, which are the fastest tuners on the market, as far as I know. Anyone who thinks the QC tuner is fast has clearly not tried them 
Ultimately I sold them because the QC is good enough for me personally. But it’s not great and could be improved for sure.
You can hit a string multiple times in a row and sometimes it will randomly jump to a different note or go blank for half a second. Or if you tune one string, then mute it and move on to the next one, it will sometimes be on a completely wrong note at first.
During live isn’t possible…
I’m sorry, do you mean you can’t use the tuner when playing live?
this is the weirdest factor to me. Some love it, others have nothing but trouble. Maybe depending on age of the unit there are different components involved.
I use a boss clip tuner… but I would prefer to use the Quad cortex if it was more precise instead of jumping from one extreme to the other…
Listen, you’ve gotta upload a video showing the QC’s screen while you’re tuning. If you’re insisting that it really is that bad.
I’ll do it as soon as I have the chance’… currently because of my work I have little time… but I’ll do it next days…
Any chance that you’re using it with an acoustic or perhaps a hollowbody electric? The discription of your tuning issue is so completely different from my experience. I have a buddy who uses a QC and he has never complained about the tuner (and he complains about everything). I keep thinking there must be an external factor that’s being overlooked.
This is why I use an always-on external tuner. If I need to tune when I’m out for a line or two of a verse, by the time I switch the QC into tuner mode I need to be back in.
QC tuner has sometimes difficulty with my Godin piezo acoustic, but works well with electric guitars.
The best tuner for me is Polytune, but I’m satisfied with the QC tuner.
Any plug-in tuner can struggle with acoustic or hollowbody instruments due to external sounds exciting the guitar body, especially at loud stage volumes. A clip-on tuner would likely give better results for tuning mid-set. Nature of the beast, unfortunately.
On a semi-related note, I recently watched a “rig rundown” for the guitarists with the band, Heart. One of the guitar techs uses a tuner, mounted to a regular humbucking pickup, for tuning acoustics. He just stands with the guitar strings next to the pickup so that the signal to the tuner is less influenced by the band volume. Obviously, this isn’t applicable to using the QC tuner but I thought it was a pretty slick solution.