So, I've been leveling a warrior, and every time I get dodged or parried when using heroic strike I lose my 15 rage. If a warrior uses a rage ability that is dodged, parried, or immune, no rage should be lost. Probably same issue exists for druid (Bear forms)
There is a similar mechanic for rogue and druid (Cat form) as well, they should only lose 20% of current energy cost for a dodge, parry, or immune.