Update: We have traced it to power management settings. When the Intel Bluetooth device is set to not be turned off by the system to save power (there is a checkbox in Device Manager when properties is opened, in the Power Management tab), all symptoms vanish. The system, however, is then unable to enter connected standby and power draw is very high -- the network also fails to connect upon resume. But this is a lead. I hope this helps the Intel team fix this critical bug in essential bluetooth functionality.
Thank you for the information and feedback provided. We will notify our engineering department. It is important that you know that Bluetooth and Wireless share the same antennas and this can directly impact on the wireless connection.
Have you tried to use this keyboard ina different system to see if the samething happens?
If possible, provide usthe full information on the keyboard such as the manufacturer and model so we can repdoduce the issue.