My new AirTags are not able to find tagged devices

The AirTag must be within Bluetooth range of an Apple device to relay and report its location.

If out of Bluetooth range, its location won’t be available and won’t be relayed.

Apple doesn’t publish a Bluetooth range for AirTag.

Range estimates are from ~10 meters to ~240 meters, the latter based on the Bluetooth 5.0 U1 chip used in AirTag.

Assuming that you mean an AirTag (?) and that you’re using the FindMy app on one of your Apple devices. …

… is the AirTag in a location where it can be found?

(i.e. Near other “cooperating” iPhones which themselves ALSO have live data connectivity.)

Restated: an AirTag by itself out in the middle of a large pasture can’t be “located.”