macOS Bluetooth menu bar show BLE Devices
This is expected behavior.

BLE (Bluetooth Low Energy) devices aren't broadcasting at all times like classic Bluetooth devices, they respond to "advertising packets" sent by the scanning device (your Mac).


  BLE devices are detected through a procedure based on broadcasting
  advertising packets. This is done using 3 separate channels
  (frequencies), in order to reduce interference. The advertising device
  sends a packet on at least one of these three channels, with a
  repetition period called the advertising interval. For reducing the
  chance of multiple consecutive collisions, a random delay of up to 10
  milliseconds is added to each advertising interval. The scanner
  listens to the channel for a duration called the scan window, which is
  periodically repeated every scan interval.


When you hold Option while clicking on the Bluetooth icon, you're telling it to "send the advertising packets to discover the BLE devices".