Can you please check these few posts? It looks to me like copyleaks is giving false results. 
I have no doubt in mind that these posts are written by AI. Every post shows 100% detection by Copyleaks and GPTzero (except number 4, which shows 76% GPTzero and 100% Copyleaks) which IMO is the gold standard for detection.
Why do you think Copyleaks is giving you false positives?