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".