This is happening for the past couple of days:
So whenever I go to The Observatory and buy a Prophecy at the Telescope it deducts my favor for the price the prophecy originally was and then shows an empty sky.
Like no new prophecies. I then have to close the telescope and reopen it to see new prophecies.
It then shows me different prophecies and I still have my original amount of favors.
It basically rerolls the original prophecies without me buying anything. I dont think thats intended.
When it shows an empty sky, wait for a bit & the new prophecies will appear.
Sometimes it can take a while, but it will eventually roll new Prophecies.