If it happens with the pilot switch as well then I have the same issue. Odd thing is mine did not have an update between it working and not working. I did have to load a default key bindings file [the one that houses your assignments not the .lua that has the switch "code"] because I erased all of my bindings by accident [wrong clear button] My code is still correct down = 1 up = 0. Still no dice on how to fix it.
Update: Did some playing around, edited the up to 1.0 and the down to 0.0. Now the "spring loaded" feature is back, but backwards LOL. I also have two lines one acts like it has a syntex error, the other lets me bind stuff to it.
Update Update: I got the controls to work again. in the input/default.lua file copy the fuel dump command
{ down = fuel_commands.DumpSw, up = fuel_commands.DumpSw, cockpit_device_id = devices.FUEL_INTERFACE, value_down = 1.0, value_up = 0.0, name = _('Fuel Dump Switch - ON/OFF'), category = {_('Left Console'), _('Fuel Control Panel')}},
and rename it to 'Fuel Dump Switch On/Off Working' name doesnt really matter you just need another input to bind. Then go into the game and bind the new input.