We have sometimes seen the Send on/off being "flipped" from time to time. If you have Send set to "off" and it is showing up as connected in the App (shows the serial # on the screen), but when you turn Send to "on" it disappears, then it is flipped. It "looks" connected, but won't send times when Send = "off". Usually the fix for that is to make sure Send is set to "off" and plug it into a USB charger for at least 30 seconds, then disconnect the power. That will usually do a "soft" reset and it usually flips back to normal, so when you turn Send back "on" it shows up on the iPhone. If that doesn't help here is what to try next:
First make sure that you have the latest firmware on the ShotMaxx. It is 3031 as if this post. Get the Burn ShotMaxx app from Double Alpha's site and download the Firmware file. Run the app and update to the 3031 version. You can do this even if you already have 3031 on it. That will also do a "hard reset" on the SM. You can also try rebooting the iPhone to make sure everything is good there, but we have found that the iOS devices are usually pretty stable for Bluetooth (Android sometimes requires a reboot to get it working properly).
Please let us know if that helps?
