Fiery Intervention does not cast if there is any indestructible support in the battlefield.
No matter there were other supports or creatures, it does not cast.
I don’t know about you, but I could cast if there was a different support, just not if an indestructible one was the only one. The inability to target creatures is sad, but does go with the card text.
I had a similar issue during the last coalition event. I was unable to cast FI on a vampire token