Mute Button Stuck on while using Intercom, "Key Not Active"

[Kirill Klimakhin]

Cisco 8841/8851 phones, all of them seem to be doing this now all of a sudden. 

Intercom was working fine for a few months. 

Any ideas? CUCM 11.5

[Manish Gogna]

Were there any changes recently like phone firmware upgrade or cucm upgrade?

Is the intercom configuration in place?

Can you try removing and re-adding the intercom config for one of the phones and see if that helps.

Manish

[Kirill Klimakhin]

Hi Manish, 

There were no changes made to the devices nor the CUCM itself, no firmware or SR updates either. 

Attempted to power cycle the affected devices, same result after they came back up.