The proximity mechanism is not very stable. The signal can constantly change (even when the key lies in one place). Within a few seconds, the signal level can vary by 30-40 units! It is influenced by a lot of factors: mobile network and other Bluetooth devices. These are the properties of the technology itself.
According to our observations, we recommend setting intervals between the values of at least 40. We have chosen the optimal values:
LockProximity - 30;
UnlockProximity - 70.