console not reporting result of commands, not saving command history

Both in worlds migrated from prior snapshots, and newly generated worlds, command-line results not displaying in console, chat-log, history. 
Examples: "/seed" won't print the seed to the console.
/say [message] , won't print a message to the chat
/locate, won't return any result
---no errors, no history/logging, nothing. May also affect earlier snapshots, but was not extensively tested.