hello @Shampoo.Jones SJ welcome to the Type One Nation forum. There are a few members here that have the 670 with varying levels of success. I want to add my 2 cents: the CGM transmitter can be at fault when the pump can’t find or detect the CGM… sometimes it takes several calls to Medtronic to get them to replace the CGM transmitter - and that part will be up to you and how long you can stand being put “on hold”.
That being said, the pump works without the sensor and so having a good pre-programmed basal rate and knowing and testing that your carb ratios are good, will help you for when the feedback is not operating.
I hope you have access to all the resources you need, pump programming is a bit of an advanced subject and so if you are new to pumping or newly diagnosed it is something to focus on. A CDE and pump trainer can get you to a point where all the manual settings are right - but I must say that it took several months when I started pumping to get the thing to behave itself.
good luck and please reach out if you are having any specific problems…