I'm having the same issue a lot of people are having since the Oreo update with bluetooth.
Factory reset, clearing the cache and data for Bluetooth 8.0.0/Bluetooth 6.20.63/Bluetooth Midi Service 8.0.0, ejecting my storage card, turning off bluetooth scanning, turning off bluetooth file sharing, turning off bluetooth SmartShare Beam, changing bluetooth options in Developer options, and excluding bluetooth from power savings have not fixed the issue.
Once every 45 seconds to two minutes, the sound will cut out and back on when listening to any sound producing app on bluetooth on any bluetooth listening device. I'm just posting this so it has visibility, but it seems that on other carrier's websites, the buck is being passed between them and LG with neither party wanting to rectify the situation. It seems that LG has not posted anywhere themselves that they know the issue is occurring.
I listen to audio on my phone almost exclusively on bluetooth, and this is a big issue for me. I just want it fixed, my phone replaced, or a different phone, as there are many people with the issue, it's been going on for a while, and no one has been able to lock down a permanent solution.
Note: I made a new topic due to my reply in another one being auto removed (most likely for posting links where other people are having the same issue.)
I experience this issue even with the phone booted in safe mode, so I don't think it is anything other than defective phone and/or the OS itself.
Have you tried un-pairing all devices then cleared the Bluetooth cache in the app manager and rebooted?
Clear the Bluetooth cache steps:
Now go back and try to establish the connection again with the desired device.
How many devices are connected?