Did you get a message from the server manager stating "mod details not available"?
The server manager uses Steam's Web API to get most of it's information regarding mod versions and details. Without this Web API, the server manager would have to download all mods every time to determine if it needs to be updated or not.
The problem with using the Web API is that a key is required. The key has a daily limit and if exceeded, can cause data errors to occur when the mod information is requested. The server manager has defined it's own key, but with the increase in usage of the server manager, this has caused the server manager's default key to exceed it's daily limit on more than one occasion.
To prevent this daily limit affecting you, you can register for your own Web API key. This then allows you to operate the server manager without being affected by other users.
Here is a quick cheat sheet to show you how to register for your own Web API key.