I also am using IOS and have 1 habitat that doesn't respond when I select it. I can't feed those dragons or move or upgrade the habitat. For me it is a Zodiac habitat that is located in the uppermost corner of the largest island. (Not any of the new lands) I tried to invite you to see if your habitat is located in the same area, but as soon as I pressed invite my game crashed, and now crashes every time I press the invite button.
Other than this my game has been running fine, all images downloaded etc. I have sent in a ticket to support about the habitat, but no human response yet.