Bluetooth mouse disconnect

So here's an interesting problem...

I have a Surface Book (i7 fully loaded) and am using a Logitech Bluetooth mouse (in the past I have used an MS Sculpt Comfort mouse with the same problem). Running the Windows 10 Creators Update (x64) and all software/drivers are up to date. I am using a Surface dock, but the problem occurs regardless of whether I am connected to the dock.

In DOPUS I select a group of files to copy/move (could be a full directory or just some files). Once selected and the operation is specified (either copy or move), I go in DOPUS to the target location. About half the time when selecting the target, I lose connection with my mouse. Sometimes just launching the Bluetooth Show Devices screen will reconnect, but a lot of the time I have to either restart my computer or remove/re-pair the mouse to get it back.

Worse, though, if there is currently a file copy/move already in progress, the disconnect causes DOPUS to hang and eventually blow up with an "unexpected network error" (which is so much more annoying than an expected network error). Generally I can just restart the operation - no files are locked, and nothing appears to be lost. It just broke, that's all.

The AVASTAR Bluetooth stack seems to be working literally everywhere else. And I can consistently make this happen ONLY in DOPUS. It does not happen in File Explorer. I mean, at all.

I've tried looking for ShellExView extensions that might be at fault, but I can't find any hung or in anything but a normal state. Bluetooth works perfectly in every other way. I do not have Bluetooth File Transfer enabled nor do I use it.

Any ideas where to look? File copy and move operations are just about useless for me with this problem...

Opus isn't involved at all in Bluetooth mouse connections, so whatever is going on is, at most, something Opus might be triggering, with the problem somewhere else.

Possibly connecting to network resources using Opus is triggering an extra-paranoid mode in a firewall or antivirus which then starts blocking network and radio connections, including the Bluetooth mouse. (That would not be something we are doing on our side.)

Explorer not triggering the problem may just mean things are treating Explorer differently to Opus. e.g. Antivirus/firewall software may already be set to ignore Explorer while it thinks Opus accessing a network folder is suspicious. (It's also possible that there is a bug that Explorer happens not to trigger, and the vendors only tested with Explorer.)

Try deactivating energy-saving for the bluetooth-mouse (in device-manager). Also using built-in-BT-driver from MS/Windows could help.