Aherys_ answer is correct. Just to add further to this.
You are getting confused with the editor window listed as “Server”. What you are seeing is NOT the server.
You are running a listen server, which means the first client creates the server, however the window itself is showing the client’s view for that server. So you are seeing it working in that window believing it is the server, where actually, you’re just seeing a client the same as the other window.
Follow Aherys_ advice, make sure your actors are set to replicate correctly and you should be good to go.
Also, logs are your friend! Keep an eye on the output log and you will clearly see where things are executing and you will probably see some messages directing you to the problem.
Good luck.
Alex