Both our iOS and Android phones have been completely unreliable for presence in the ST app. If you have an Alexa device, here is a link to how I’ve set up presence for the two people in our house.
Another option now that IFTTT and ST integration has returned would be to do a similar setup as I described in the link, but using IFTTT for geo-fencing and having it turn on/off a virtual presence sensor in ST.