One of the many guest set-up parameters available is the ability to control how many guests can share the same mobile device to sign-up for the loyalty program. This prevents abuse from those guests who may try to make multiple multiple accounts on the same device.
Typically, this error occurs when if someone (friends, children or spouses) have already used the device to sign-up for loyalty.
"Guest Per Device" is found in:
Cockpit >>> Guests >> Guest Validation. In the example below, the parameter is set to 1.
Even if you're unable to locate an account if someone (A friend, her kids, significant other, acquaintance) signed up for Veggie Grill Loyalty thru her device she will be unable to sign up for loyalty. This is due to the "Guest Per Device" set to 1 in the Guest Validation Cockpit setting,