If you are experiencing issues with your BLF lights not working then in majority of cases it is caused by Global Presence being enabled within your configuration.
Global Presence will enable presence for all tenants on the system.
Note: Enabling this option will prevent you from monitoring presence status for extensions on the same tenant, unless you enter tenant prefix in front of extension number (e.g. 2001001 for extension 1001 on tenant 200.). However, setting Global Presence to Yes, will prevent you to use BLFs to monitor parking lots on your tenant as their numbers do not have tenant prefix.
If Global Presence is enabled you would need to make sure to set your BLFs as Extension+Tenant number or disable Global Presence in case configuration is set to Extension number only.
Global Presence option can be configured on UAD as well as Extension level.
Navigate to Settings -> UAD -> Edit UAD -> Global Presence
Navigate to Home -> Extensions -> Edit Extension -> Show Advanced Options -> Global Presence