I do believe the LCD is on in the TA and I tell newer flyers about it usually when there. It uses a process that is also used in the PADLOCK view mode I believe.
However your commands might be slightly off, then again mine might be also. Here's what I use in the TA.
Cntrl-Tab to enable FRIENDLY LOCK
Once enabled:
Tab to cycle through the targets in your field of view.
Shift-Tab to highlight the centermost target in your view.
Views do NOT have to be straight ahead, you can highlight any target in any view if you have LOS, Line Of Sight, on the intended target.
You will get the green + for the LCG when highlighting a target. You might get two +'s because primary and secondary guns will each get a +, fyi. If you want to single out the primary gun I sometimes take a DT, Drop Tank, so I can select that as secondary weapon and don't get the associated crosshair. The F11 or padlock view will track that target if you keep LOS on it. You loose padlock if you loose LOS of the target I believe.