Hello
I did a test in my lab but unfortunately I could not duplicate this issue. These were the steps executed.
1.Create user ( Bruno) with read role
2.Create Stream /w rule a specific source ( Just to get some data)
3.Click on share with “Bruno” as viewer.
4.Log into with Bruno’s credentials that were created.
5.Navigate to stream for sharing
6.Open stream to view Messages
Unless you have some other configuration within your environment that we don’t know about. I’m not sure what your problem is. We would need more information to resolve this issue and if you unsure what you need please look here for better clarity
Hope that helps