I’ve had the G7 for about 7 days. My sensor yesterday and the day before started not reading saying “…wait up to three hours…” Finally it stopped for most of the day and I called Dexcom and they told me to remove it, wait 10 mins, and then put on a new one. I did so. That was yesterday afternoon. Last night, I got an urgent low, 2.3 or something. I got up and tested, and I was 5.1. I calibrated, and checked a little later, and my pump was completely stopped. Is this normal for the Dexcom to stop all deliveries on the pump? So I calibrated the pump (which I didn’t do when I changed the dexcom to the new sensor early, I did do it with the original sensor as it was my first G7). So, I entered the 4 digit dexcom code in my pump and it was back on and working, but then I got another urgent low (which was false) and it said it wouldn’t recalibrate. This went on all night–false low after false low. In the morning, I had a real low. Today, it’s been working fine. I have not enjoyed the G7 experience so far! I am hoping this is just a rocky start. I hate not feeling like i can trust or rely on the dexcom.
Sorry to hear about your problems with the G7, but thanks for letting us know your experience. I haven’t made the switch yet - wondering if I should go over to Abbott, as I think they work with the Tandem now???
Where are you placing the sensor? Try another location.
Yesterday went better. It said I had a bit of a low (not too bad like a 3.9 or something) in the night, but didn’t check it with a fingers stick, I just ignored and managed to get back to sleep. So far so good today.
First time was on my stomach, next time was on the back of my arm.
The first 24 hours of a sensor are the worst!! 
I feel your pain…
My personal rule is not to calibrate at all in the first 12 hours. The graph will usually be accurate about how much my BG goes up and down, but the reading itself will be bad. The BG reading tends to be lower than I actually am. I think someone here recently speculated that defaulting to reading low could be a safety measure? But an annoying one…
I broke my own rule with my latest sensor. It kept saying I was 50 (2.7) all through the night. When I checked and was actually 120 (6.6), I broke my usual rule and calibrated. Then it jumped to saying I was 160 (8.9) 
but hey, I can sleep through a false high. I turned off Control-IQ so the bad readings wouldn’t keep affecting insulin delivery.
The graph became unreliable for the next day, very jumpy. I had to calibrate 5 more times throughout the day to get it to read accurately. Whereas when I follow my rule and don’t calibrate, I feel like it reads pretty accurately by itself by hour 24.
Not fun! I’m sorry you’ve been struggling!
Uggh. That’s terrible! I am mostly disappointed about the night time, as it was my only consistently good time in range where I’d rarely have a low, and be almost flat line all through the night at a good reading. I’m so tired from being woken up repeatedly every night since the G7. I also don’t trust it. I also don’t like that it runs lower than my finger prick says, as I’d prefer to not be unknowingly running high all day. I am going to see if I can go back to the G6 after I’m through these boxes.
That sounds exhausting! Is it still reading significantly lower now that you’re in day 2? Usually mine will be within 10 points (0.6) of my finger pricks after 24 hours.
Whatever the case, I hope your current sensor settles down soon!
I have had a few of the jump-down G7s. Fortunately most of them are not like that, but I had one that jumped down all 10.5 days
. When I get one I have a snack before bedtime to run my sugar up and make sure it doesn’t wake me up for nothing in the middle of the night. The screenshot was early in the session but shows what happens–sudden drop of 30 or more points.