We usually restart the sensor at day 7 and have no problem making it 14 days or so. This time (day 7) I can't restart the sensor. Every time I try sometime during the two hour calibration it stops filling in the circle with green and instead goes back to the dreaded ???. It has happened twice with this sensor. Giving up and putting in a new sensor. Anyone else had this happen?
We've seen ??? during the green period, but eventually it asks for a BG. It seemed to happen when the BGs are fluctuating a lot. It still surprises me when a trend arrow appears with the first calibration, but it's been reading and tracking without numbers. The ??? can also appear if the transmitter isn't completely clicked in on both sides.
We see that during the 2 hour start up sometimes. At the two hour mark, though, we still get the calibration sign and all is well. I'd give it the full two hours and see if it works for you.