Hello Michaela5215,
Thank you for using Apple Support Communities. We'd like to recommend some steps to see if we can get the issue sorted out. First, you'll want to make sure that you allow notifications for the Find My app: Change notification settings on iPhone
1.) Navigate to Settings > Notifications > Find My.
2.) Make sure that it's set up to receive notifications.
This resource has more details as well: Set separation alerts in case you leave a device behind in Find My on iPhone - Apple Support
You can only set up a separation alert from the device sharing your location. You receive an alert every time the device sharing your location separates from the device you set an alert for.
1. Tap Devices at the bottom of the screen, then tap the name of the device you want to set up an alert for.
2. Below Notifications, tap Notify When Left Behind.
3. Turn on Notify When Left Behind, then follow the onscreen instructions.
4. If you want to add a Trusted Location, you can choose a suggested location, or tap New Location, select a location on the map, then tap Done.
5. Tap Done.
Also, in Find My, make sure that that specific location isn't listed under "Notify me, except at". If a location is listed there, you won't be notified.
We hope this helps. Thank you for using Apple Support Communities.