I was wondering if anyone has ever encountered this issue where the chat icon in their Webex is literally missing? I can't view or reply back to any messages. 
This looks as if your administrator has enabled Webex in phone only mode, which I believe is something that must be enabled by your CSM. It allows an administrator to deploy the Webex App. I would reach out to your CSM to see if this is true for your Org or open a support case.
