I have an email that was sent from my EM client but i am not able to see it on Gmail web application

I have an email that was sent from my EM client but i am not able to see it on Gmail web application, the reciever adress shows up as hidden and there is no info in the email. it is contained in another email chain which is from 2014, shows as sent from my account to “hidden reciever” but its in my inbox and not my sent items. Is this just a bug in the app or should i be worried?