What endpoint is the Touch 8 paired to, and it's software version?
Is the Touch 8 directly connected to the endpoint or over LAN?
If the endpoint software was recently upgraded and was running an older version prior to TC7, you could be hitting one of these issues: Field Notice: FN63983, CSCun63651.
You could try to upgrade the endpoint to the latest software version, if that doesn't work, you can try to factory reset the Touch 8, see factory-reset-touch-8.