Self-powered BLE switch (TEL0173) very unreliable

Hi all,

Wondering if many people have tried the self-powered BLE switch (TEL0173). I have just bought two, and while they are super cool, they seem to be very unreliable.

I can see BLE advertisements from both switches in the iPhone app (NanoBeacon BLE Scanner) and an ESP32 (ESPHome). But I would say only one in four button presses results in a BLE advertisement that can be seen by either device.

And yes, I've connected the included antennas.

For reference, here is the relevant ESPHome fragment I am using:

Any experiences / suggestions would be most welcome!