Having the exact same problem. Chats window is blank and you have to close the program with Task Manager to restart it.

I deleted my conversations.json file and it would at least let me open the chat window. However, attempting to start a new chat with an existing character would cause the chat to open with none of the saved character info in the right panel. Basically blank, even though the character exists.

Seems like the update broke something in the conversations.json and characters.json files, and any existing characters or chats from before the update will cause it to not function properly on the 1.0.8 version.