Dragon rage bug?

[Metroplex]

I don't know if this is a bug but during long fights and when you have depleted your rage, the Dragon stops generating any rage no matter how much damage your troops take, also if you bring up the dragon's abilities they are all greyed out (obviously because there is no rage) but it says it is resting but no matter how long time passes it never gets out of that 'rest'... annoying when you want to gather the last buried treasure but you have no rage to do so!