Front derailleur not reaching the "L" screw!
Either the inboard travel of the derailleur cage is limited by the adjustment of the shifter cable rather than the limit screw, or there is something impeding the derailleur movement.

if the shift cable is tight and you can move the derailleur by adjusting the barrel adjuster then the derailleur is not up against the limit screw.

If the cable is loose, or you can manually push the derailleur up against the limit screw there is something impeding the derailleur movement. Excess friction or binding of the cable in the housing is a common cause of this. 

You can pull the cable out of the housing, clean and lubricate with a small amount of chain lube, or just replace the cable and housing as they are not very expensive.