Hey, thanks for your detailed feedback, much appreciated!
Hmm, this seems a bit weird, especially if your plugin is updated to the latest version. The 'Edit Related Posts' button shouldn't be appearing at all, if your stats are turned off (afraid those two features cannot work without each other).
Would you please be so kind and turn your stats on for a moment, just to see if that error message is still appearing over there? Would love to know if the problem is persistent or not, if that's OK with you.
Thanks for all of your help and please do let me know if you have any more questions what-so-ever — I'll do my best to help you out!
Take care & have a nice day!