I am having a problem with the chat feature of the web and email interaction manager. Chats are one way, agents can recieve them but the client cannot recieve the replies or any chats from the agent. I have tested with browsers that have 'MeadCo Security Company' add-on installed and enabled and it works fine. But it doesnt work on customer browsers that dont have the add-on installed. I have tried enabling the chat setting that requires the customer to install it but it still does not prompt the customer to install it
The EIM 4.3.1 ES4 patch came out a couple of days ago. I dont' see anything specific to your problem in there, but it may be worth a shot.