Logs might give clues, but Vero 4K’s BT shouldn’t be causing this. It’s more likely that the device will standby.
I understand you don’t want to fall back to IR, but there are a lot of Harmony users on Vero 4K and IIRC you are the only other one controlling the device with BT.
Seems similar to HowTo - Reenable and pair to a Bluetooth Device automatically.