Check their description. Their actual max range is fixed and it's shorter than max range of your weapon which devs did not predict would ever take place.
the cast range is 'Melee' which scales with range stat, hence why its cast-able. And physical aoes who are 'melee' range which are coded correctly in their skill stub (the c++ header for the skill before compile) which also happen to be aoe such as
Surf Impact still work at this range.
These skills are written incorrectly in the stub or are a wrong 'type' id to handle such a range even though they should. It is a bug where it is going with the aoe radius range as the max range and the current 'Melee' range value at the same time causing confusion for the server (GS)
as for what causes this bug I have no clue. One of these skill types from 2008 may be buggy at this long range but that wouldn't explain why 'Surf Impact' works just fine.
