I would have to totally disagree with this statement. I'm sure you would not like to do a Factory Reset, but if I was to guess (not knowing what your done with your device) is it's either a setting that you have changed since you started using this device, or it's another app causing your problem.
I have an AT&T version and a Pure Edition device, and I don't have this problem with either device.
The reason I know it's going to be an application setting, is because with the Google camera app, I don't have that issue at all no its not faulty hardware because the camera and the flash on my phone are fine. Yeah I'm not wiping my entire phone for this one application setting lol that crap isn't happening just like anyone else on this forum. I would wipe it , however I'm sure it would but that's not going to solve what's wrong with the application itself is what to say that I was the phone, & a day later the application doesn't go back to doing the same thing? I reset my phone maybe for almost no reason? Trust me, I thought about this process long and hard a couple nights ago at work, it doesn't make sense because am i old original first gen Moto X I didn't have this issue and I just recently started having this issue I didn't change any other variables or Settings app on my phone at all it just started happening, that's why I tried to clear the cache, & 4 crash the Motorola camera application thank you no help. &, but I should have to do that every single time. And it seems like whenever I would quickly twist the phone to launch the camera app, I will get that camera error screen which would make me have to delay my shot by closing the app relaunching it and praying to God I can still get that camera shot if you know what I mean.
I mean on a lighter note, I have been using the Google camera app and well there's no shape to twist activation feature, maybe it's just me but the user interface to you I have the app runs a lot smoother than the Motorola camera app does.
Sent from my custom 2nd Gen Moto X built by moto maker running lollipop 5.0