On 3CX V14. Our Yealink t42 phones with firmware 220.127.116.11 lose BLF presence after a while. We have other extensions configured as BLF and they do not show if someone is on the phone (BLF buttons stay green). We attempted to manually install firmware 18.104.22.168 but it will not take (it goes through 'updating firmware' but stays on .110). The only fix we have found so far is to reboot the phones. We cannot tell how long the reboot is good for before it stops working. Has anyone seen this or have a fix for it?