Fuel Scoop
You need a fuel scoop for the supercharge to work.
I forget to equip one all the time so dont worry about it lol
Is it turned on?
Did you have it on when you went through then? Because if you didnt thenyou need to go through again.
Otherwise Im not entirely sure whats occurring.
Did you plot a route without selecting neutron boost therefore the next destination is 14ly away, or is it showing 14ly on the functions panel of your ship on the right?
The only final thing I can think of is that you may have mistaken is that 14ly is your supercharged jump range.
Sorry if I havent been any help lol
Maybe take a video of it and post it on the bug reporting if you think its a bug
Cool, glad its working
Basically they increase your jump range by a factor of either 50% (for white dwarves) or 200% (for neutrons) so if you have a small jump range to begin with you wont notice that much of a difference really