I found this which explains where to add the -console in steam to re-enable the use of F5 server commands. I can verify this worked to re-enable, however when using the "save" command console reports only "saving" and never confirms a save has completed. https://valheimbugs.featureupvote.com/suggestions/172792/read-here-console-commands-changes-after-v01486-and-forward
I am also looking for this answer. On the client side or on a dedicated server you are running locally on windows you can just add the -console to the start_headless_server.bat file and I think that is suppose to re-enable the console ability. However I can not figure out a way to edit this file on SS(also wouldn't think it would matter as I assume these servers are running on Linux) I just get a error every time. I am using Filezilla to FTP that file from local to SS server. I have no issues with moving files from SS sever to local. I just want to be able to world save on command as we have had 3 instances now of the server not saving our world data.
Error: File transfer failed
Status: Retrieving directory listing of "/valheim_server_Data"...
Status: Directory listing of "/valheim_server_Data" successful