Are you running SandBox through windower?
Do you have other chat detection/on event functions active?
I had a small issue with this after reinstalling on a new PC, SandBox fixed it, but I am not sure what caused it. Hope this helps a bit.
I started using chatmon recently, would that cause such an issue?
Edit, unloaded Chatmon...did not fix the issue.
Are you sure that’s not the chatporter plug-in?
I don't have that installed.