You need to go into FTX Central, Settings, Configure FTX Global Vector. Once the new window opens, go to the Airport Elevation Corrections pane and in the Manual Configuration search for KLAS in the righthand serachbox. If an entry is found, press Disable. Now it should work as normal.
Note that this solution is only if you have FTX Global Vector Only, if you also have their FTX NA Socal the link above provided by Umberto should do the trick.