Looks like Flo v2 API may require a heartbeat keep-alive API call periodically for the server side to keep refreshing.
POST https://api-gw.meetflo.com/api/v2/presence/me
Headers:
authorization: XXXXX
The web interface posts a heartbeat every 30 seconds.
Note: Since there is a Flo integration built into Home Assistant now, the custom integration is now not being maintained.