To help reproduce this issue, can you confirm your O/S version and Atlas cluster type (eg M0)?
If you want to work with documents in Atlas and are having trouble with client applications, you should still be able to use Atlas’ built-in Data Explorer feature.
You can connect to MongoDB Atlas using any drivers or tools that support your cluster’s MongoDB server version and implement TLS/SSL. Free/shared tier clusters (M0, M2, M5) additionally require TLS with SNI support.
Robo3T is unfortunately not actively maintained and has a large number of unresolved (and untriaged) issues including compatibility and stability problems. It also embeds a specific version of the
mongo shell, which can cause unexpected issues with different major server releases than the embedded shell version. Most MongoDB admin tools use a supported driver API for broader server version compatibility.
I definitely would not recommend using Robo3T for working with any production data or essential data until it is more actively maintained.