Thanks for the input guys, I have setup IW4MAdmin as per their guides from the start over 3 years ago and always had logsync set to 1 and g_log is set. All logs are correct and named different on each server So that's not the problem.
g_deadChat was never a dvar within the server config I have so I have now set it but like I said even chat whilst playing ingame didn't get through sometimes.
I will monitor it
At least I know now that its not a global issue and can fault find and track down whats causing the issue.