Cannot log in with a device code

[Trillium_Farm]

I logged into the web UI. I generated a device code, emailed it to myself and my partner. I wanted to make sure it would work for him. I logged out of my Square app, closed it down. I click on my email, copy the device code. I tried to sign in with device code instead of my login - I pasted in the code. I just downloaded the app a few days ago so it can't be wildly out of date. But it says "Login Failed: Incorrect device code. Please check your device code and try again."

I tried again about 3x, even looking letter by letter. Is this feature just broken?

[RHatch]

You can only use one the code on one device. If it has been used you need to create another one.  Also make sure you are not copying a space before and after it.  The device code is not a password you must select "Use a device code" on the sign in screen.