Hi,
Sound like the problem I have with my iMac Pro which randomly, simultaneously disconnects all Bluetooth devices and then thirty seconds or so later reconnects them. This happens on a range of Bluetooth devices including keyboards, mice and headphones from different vendors. I've worked through all the resetting of the Bluetooth module, creating a new user account, reinstalling macOS; creating a new boot partition. Last week, AppleCare arranged for the machine to be collected and a complete new motherboard was put in.
It's still happening.
Not sure there is very much in the iMac Pro that isn't on the motherboard, so either I have been very unlucky and got another machine with a dodgy Bluetooth module, or the problem lies in software.
Apple Support are on the case - but so far no explanation of what is going on.
I recommend people get in touch with them and file a report explaining all the steps they've done. I'd also recommend catching as much data as possible by running the Console application, clicking the Start button and then entering Bluetooth in the Search field - this will only show messages relating to the Bluetooth functionality. On my machine I get a host of errors when Bluetooth falls over that the machine is unable to send data packets. You can then use Copy and Paste to share this information with Apple who will provide an upload link for information when you file a case.
So annoying...
