Messages going missing

Buyers sending me messages but I'm not receiving them. I'm replying to other messages and ticking 'Send a copy to my personal email address' but none of the emails are being copied to my email???

Multiple buyers commenting saying they've sent messages, or included message to seller at purchase, that don't appear, and ebay claim nothing is wrong.

I can prove I'm not getting copies of any messages sent. Something is wrong with their messaging system.