@Loz Hi Laurance, and welcome to the JDRF TypeOneNation Forum! You have found a very good Forum, and quite welcome to ask anything “diabetes”. and to offer your insight too.
I’ve been using Control IQ since January, and really like most of how it helps me. In addition to what @Joe and Dorie have offered, I will suggest something I’ve observed during my many decades living with diabetes.
You didn’t mention “how long” your daughter’s pump may have been turned off, or what she was doing, eating, during that time. If she was without needed insulin for an extended period, it may take her body a while to recover - like when she was diagnosed with diabetes. At least, that has been the way with me when I’ve let my glucose run wild.
You can look at tell a couple of things quite easily about the Tandem pump by looking at “Pump History”. You can see exactly how much insulin, both basal and bolus, has been delivered today, yesterday, etc. You can also read the Average per day delivered during the past seven days, the past 14 days and the past 30 days; compare these average readings with today’s delivery summary. This will let you know if the pump is currently working properly.
Another thought, and I don’t know your daughter’s age, to get your daughter to regularly charge her pump. suggest/Require that she periodically, you set the day, upload to t-Connect and send you a Summary report. This will require that her pump is plugged into a computer, and charging. unless she uploads wirelessly to t-connect as I am doing.