My bluetooth is turned on, but my device is not listed and will not sync. Bluetooth icon is greyed out on the screen of my device, but turned on in Settings.

My iPhone 6 abruptly stopped syncing with my Jawbone UP today. When I tried to get it to sync, I noticed that the Bluetooth icon at the top of the screen was greyed out. I checked my settings and Bluetooth is turned on, but my UP is not listed as a connected device. The UP app is not showing any error messages and appears to be connected to my phone, but tells me it hasn't synced in hours. I have both restarted and rebooted my phone, to no avail. What should I do next?