Unable to /op player or manually add player to op list while online-mode=false

When my server is running in OnlineMode=false I cannot /op players nor can I add players to the op list using the new or old formating code. The server reports that I successfully /op'd the player, however the players are not op.

Once I switch to online-mode=true players that have previously been defined as /op are op. But not in online-mode=false.