When an invited user is sending me messages, I can't read them but they can read the messages I am sending.
We see this is cases where you have ignored a user. You can ignore a user in a few ways. Either you have gone in to the user's information and clicked on 'Ignore', or you have been invited in to a room and selected 'Decline and ignore user'.
Enter a room where the user is a member, and click (i) in the top right corner to access room settings.
Select People and click on the user's name.
At the bottom under settings, you should find an 'Unignore' option, click on this.
Ignore not receving messages