I’m no developer but I guess LR would have to enumerate connected devices when the Import button is clicked so therein maybe the root cause. Perhaps an errant USB driver, disconnected network drive or maybe a Bluetooth portable device e.g.smartphone?
It might be worthwhile physically (where possible) and/or logically removing all possible connected devices just to see if you can get the Import dialog to function normally, then re-introduce them one by one until it doesn’t.
Most devices can be logically disconnected (or disabled) in: Control Panel > Device Manager. Network drives can be disconnected in Windows Explorer. System devices e.g. USB ports can also usually be disabled in BIOS.