when you enable get location for this iPhone in the ST app, you will not see any tiles for the iPhone location in the app. One option is to create a virtual presence sensor and create two Routines to sync the virtual presence sensor - one when away to change virtual presence to away and a second to change virtual presence sensor to present. I like to create my virtual devices using this community developed Edge Driver: https://community.smartthings.com/t/st-edge-vedge-creator-a-virtual-device-generator-for-end-users/231786. There are other methods to creating virtual devices available.
If the location does not change when you leave or arrive home. You can try disabling that settings and enable it again. Of course, as noted earlier some folks have had presence issues so you may be affected as well.
There are other methods for presence. Here is just one option: if you have an Apple TV or HomePod or HomePod Mini: https://community.smartthings.com/t/how-to-use-a-meross-plug-to-use-homekit-presence-to-trigger-st-routines/238549