For my experience and recent create unitframe, It seem the Unit In Set: Unit In Range (2,4) is bugged..
For me it's work well until I enter in dungon (or had a loading screen)... After the load the flag is inversed....
the flag is set for alpha @ 1 when unit in range and 0.3 when not in range.
But after load, all my uf return an alpha @ 0.3... I change the flag for 0.3 when in range and 1 when not in range and it worked.. BUT just for the dungon... After next loading screen All my unitfram returne out of range and I rechange for 1 when in range and 0.3 for not in range...
I suggest you to create a Unit In Set: Exact spell range and select an helpful spell for range!
Then create an condition alpha shader and it's work fine!!! Even after loading !