Your system information

• Steam client version (build number or date): build date: Dec 6, 2019 at 03:34:28 / version: 1575605714
• Distribution (e.g. Ubuntu): Arch Linux (up to date as of this posting)
• Opted into Steam client beta?: Yes
• Have you checked for system updates?: Yes (there were no further updates available at time of posting)

Steps for reproducing this issue:

1. as root, run echo 1 > /sys/module/bluetooth/parameters/disable_ertm to allow pairing of Xbox One S controller
2. run steam using -steamos -tenfoot options to enable Bluetooth settings in Big Picture mode
3. go to the bluetooth settings and pair an Xbox One S controller
4. turn the controller off
5. turn the controller on

Expected result:
the controller should connect and be usable

Actual result:
the controller does not connect and acts as if it is unpaired; trying to pair it again in the bluetooth configuration screen is unsuccessful. I have to run the remove command in bluetoothctl before I can re-pair the device from the Steam big picture UI.

Additional notes:

• I was able to successfully achieve the expected result above by using bluetoothctl from the command line and following the connection instructions here (without actually installing the xpad neo driver): https://atar-axis.github.io/xpadneo/#connection
• I hypothesized that the Steam big picture bluetooth configuration page was not doing the trust step. I tested this idea by again following the bluetoothctl instructions linked above, but skipping the trust command. This resulted in the same failure as the Steam big picture configuration page. Therefore it is very likely the case that the Steam big picture bluetooth configuration page is not doing a crucial step to allow bluetooth devices to be trusted. As a result, devices are not able to reconnect after being disconnected and users must drop to the command line and use bluetoothctl to be able to re-connect the devices again.