Hello. I have the latest version of ABP installed (version 1.4). This has only happened to me today. Whenever I open Facebook, the sidebar where the chat is located is blank. It seems that ABP has blocked it. When I disable ABP, restart IE, and log in to Facebook, the chat works again. I have tried deleting my cookies, temp, etc. to no avail. I am running Windows 10 x64.
Edit: I have IE11, which is the only version that runs on Windows 10.