When the patch on December 6th was released, a feature was added to the “tab” screen to show player pings.
Currently, your own ping shows up with a “-“ (a dash, or hyphen), while the pings of other players is visible.
First, there’s a misconception that the other players’ pings are their pings to you. This is not the case; the display simply displays the pings all other players have to the server itself.
As for displaying your own ping, either this feature was not implemented fully or the failure to display is a glitch. Chances are, this is being worked on and will be fixed in a future patch.
For the time being, the only way to see your own ping is to Alt + Tab and view your ping to the server in Battlelog. As an alternative, you can ask a friend or another player in the server to tell you what your ping is showing up as. I expect this will be corrected soon.