I can enhance on this issue a little further. This issue only applies to G1 of long range mod and it seems as if only the application of the modifier doesn't work. The following steps do work:
Select a Pulse Laser
Select long range modification G2/3/4/5 and watch that everything works as expected
Select long range modification G1 and watch that fall off doesn't change
Select 50% module progress and watch that fall off now is correctly applied
Select 100% module progress and watch that fall off now is correctly applied
The long range mod should change the damage fall off start such that it equals the maximum range (see inara for reference).
However, this is not the case: