Endpoint "Transfer Playback" returns 500 error when all devices is not active

[vlaaxt]

Plan

Premium

Country

US

Device

iPhone + Android Tablet

My Question or Issue

First, I called endpoint https://api.spotify.com/v1/me/player/devices to get deviceId. All devices were inactive (for example, deviceId = XX and deviceId = YY).

Then I called the endpoint https://developer.spotify.com/documentation/web-api/reference/transfer-a-users-playback with deviceId = XX

The API returned a 500 error.

When I called endpoint https://api.spotify.com/v1/me/player/devices again I discovered that deviceId = XX had disappeared from the list of devices (but the Spotify app was still open and active on the smartphone)

After I restarted the Spotify app on the smartphone, the endpoint https://api.spotify.com/v1/me/player/devices returned back both devices (XX, YY) again.

Why is endpoint https://developer.spotify.com/documentation/web-api/reference/transfer-a-users-playback returning a 500 error when all devices are not active and why does it delete the device from the list of available devices?