Chat disabled

[libellaris]

During the last 3-4 webinars I've attended, I can't use the chat feature, even though other attendees are able to use it. For example, the host says "Put your answer in the chat." But when I try to type in the chat box, I get a message, "Chat disabled." But clearly the chat is not disabled for everyone, only for me. This only started happening a couple of weeks ago. I can't find any setting to change this. What is going on?