new dragon maybe
we all have this once (android here) even invisible flying dragons or invisible breeding ones.
I think you just have to see the timer
I know, the invisible egg thing happened to me too!
Unless I have food growing, my farms are invisible.
I had the same problem in the spring edition (really annoying when so many dragons share the same breed times now) but it's been fixed after I downloaded the new fairytale edition
I think its just a loading problem. Like my game sometimes loads up stuff, but it will h invisible, then will pop up a bit later. If i remove an egg from the nest, then place another from the breeding den, the egg will be invisible, then pop up as the one before it, then change to what its supposed to be.